I don't generally have an issue with sports day for the majority, but it should be treated sensibly with other ways to involve the small number of children who struggle with it deeply.
There's coming last, and there's coming last... ritually last, when there was zero level of competition about it, being the only child on the field is very different to having a mixed level of sucess and being last occasionally.
Sports day can absolutely be humiliating.
When I was 7, I moved schools just before the end of the year. I'd been in the school about 2 weeks by sports day. I had no friends within 100 miles. I was the smallest child in the year group.
No body asked if I could skip before being forced to perform in front of 200 children, the staff and another 200 parents.
I tried skipping. I got tangled in the fucking rope several times before ditching the stupid fucking thing and stomping alone down the whole fucking track to the end after everyone else had finished.
Then I was forced to stomp back up the fucking field alone to fetch the stupid fucking rope and walk it back down to the teachers again.
That is most definitely humiliating. On an epic scale.
I still hate that cunt of a teacher 35+ years later after only 4 weeks in her class. I hate her more now than I did then because with time I've realised what a fucking awful thing that was to do to a vulnerable 7 year old, to show zero recognition that you'd asked the impossible of them, to fail to recognise that they tried with no escape route out of the situation, and then punish them in front of hundreds of people because they failed.
The following week I was set upon by a group of boys at the end of the school day and the biggest boy in the class forced me onto my hands and knees and pulled my pants down. Fortunately my mum caught him and put the fear of god into him.
The public isolation of sports day was a green light for bullies.
I didn't learn to skip until I was 10, 3 years later.
My dyspraxic child is better at sport than me.
What I did do was get my children into non-competitive activities like parkrun and swimming lessons early so they could at least run, and get some co-ordination and not spend their entire school years being default class liability.
PE taught me to loathe competitive and team sports.
Suprisingly after all the humiliations, failiures, insults, goading and bullying that were a feature of most PE lessons, I am a fit adult, but no body is laughing at me in a gym because I only squat 60% of my bodyweight, or laughing for being mediocre at parkrun.
Phone apps taught me to run.
All school sport was a pointless waste of time.
School sport should be handled with much more sensitivity and creativity. Too many people are turned off sport for life by it. If schools don't make reasonable adjustments to sensitively include all children, it's reasonable to miss a distressing event. I am generally a "feel the fear and do it anyway" type person, but sometimes that is not the solution.