Strictly Come Dancing always seemed to me like the no-brainer reality TV show from a contestant perspective. At best, it’s seriously career-enhancing; at worst, you face the prospect of dropping out after a couple of weeks adorned in sequins.

Stay in long enough and you actually learn to dance while shedding pounds, all while taking part in a show that trades in everyone having the time of their lives rather than people falling out with each other. Not a patch on sticking your head in a fishbowl of cockroaches on I’m a Celebrity…, anxiously waiting to see if your new beau will cheat on you in Love Island’s Casa Amor, or being the Faithful everyone turns on at the Traitors roundtable.

One gets the impression that BBC executives bought into the Strictly fairytale as much as viewers, which perhaps explains why they appear to have been caught off guard by the allegations of bullying and abusive behaviour on the show. Strictly’s record has never been unblemished on this count, but until relatively recently the show has ridden the wave. Then, last year, Amanda Abbington quit the show a few weeks into the run, citing “personal reasons” at the time but later accusing her professional partner, Giovanni Pernice of “threatening and abusive behaviour” and claiming that participating in the show had left her with PTSD. Other female celebrities have also spoken about their experience of him . Pernice has repeatedly denied any improper behaviour, but the BBC is not using him in this year’s show while it conducts an investigation.

Then two weeks ago, it emerged that another professional dancer, Graziano Di Prima, was leaving the show. It transpired that junior production staff raised concerns about the treatment of his latest celebrity partner, Zara McDermott; he has since admitted kicking her in a rehearsal. Bullying allegations have also surfaced in relation to one other unnamed female professional; and the former Paralympian Will Bayley has said he feels that the BBC failed in its duty of care towards him after he badly injured himself in a jump in rehearsals.

Reality TV shows come in two main genres: feel-good self-improvement and voyeuristic guilty pleasure. Strictly is the archetype of the former; producers are looking to storyboard the “Strictly journey” of amateur dancers becoming so good you can’t tell them apart from the pros while loving every bit of the experience. The latter category includes Big Brother and Love Island: formats literally designed to bore contestants into generating the drama and tension that hooks people, in which bullying feels like a feature not a bug.

Even after producers were shocked into making changes to improve contestant welfare after two former participants took their own lives in 2018 and 2019, Love Island is plagued by viewer complaints pretty much every series, and domestic abuse charities have issued statements about toxic male behaviour on more than one occasion. Strictly on the other hand is supposed to be the ultimate win-win format: viewers enjoy it precisely because everyone in it seems to be having such a great time.

But, with hindsight, it seems obvious that it is a format that also requires care in relation to the welfare of those taking part. Like many sports, dancing has a poor reputation when it comes to the welfare of young competitors; many professional dancers will themselves have experienced bullying, misogyny and abuse in training, and their own experience will be of putting their body through hell to be the best. Participants spend long hours training together each week and the stakes have become incredibly high, not just for celebrities but for the pros too; their pay and reputation depends on how far they go in the competition, and the fame of some of them eclipses that of their celebrity partners, encouraged by the BBC commissioning spin-off shows.

There also seems to be an inbuilt assumption that someone who is a brilliant dancer and choreographer will also be a brilliant teacher and coach; it is pretty extraordinary that, according to one pro, they get no training at all on how to work with their celebrities.

The pressure cooker of social media seems to have kept a lid on some of these allegations surfacing sooner. Abbington last week described in a Channel 4 interview what she has been subjected to since raising her concerns: dozens of rape and death threats a day, directed not just at her but at her children. Little wonder then that McDermott says her fear of public backlash and victim shaming prevented her from speaking out. There may still be others who are yet to raise their experiences but have feared the consequences of doing so.

There is a reason why Strictly has remained the BBC’s flagship Saturday night entertainment for so long: 20 years after first hitting our screens, it remains a ratings magnet at a time when terrestrial channels have lost significant viewer numbers to the big streamers.

The BBC has announced changes aimed at improving welfare on the show, including production team training, two new welfare producers and chaperones for the training room. The director-general, Tim Davie, has also apologised to contestants who have complained. The question is whether this will go far enough or whether the BBC will need to give the show a more fundamental rehaul, including rethinking who it recruits to coach celebrities, and how they are supported in doing so.

The existential question that overhangs all reality television is the degree to which you can create honest and decent entertainment out of real people’s lives. For a long time, it seemed as though Strictly was one of the few shows that could pull it off. These recent allegations only serve as a reminder of how much effort needs to go into staying on the right side of the ethical line even at the most cheerful and jaunty of shows.

Sonia Sodha is an Observer columnist