Yes, my first child was fairly average all round aside from being prodigiously sociable. It does amuse me when people say school is good for socialisation; one of my main reasons for home educating was that school would have restricted my kid's social life! I could just imagine my child getting in trouble at school constantly for chatting and singing nonstop and trying to entice the other kids under the table to play. All day playdates, sleepovers which lasted several nights, multiple group camping trips, and mixed age groups were readily available to us.
No, I didn't feel the need for my child to try school first just to prove it wasn't ideal. To me, it makes sense to start off with whichever option which you think is more likely to be better. If I'm at a buffet, I don't start with the least appealing food just in case it's better than it looks. If I were dating, I wouldn't start by chatting up people I found unpleasant. If I were an employer, I wouldn't hire the people I thought less likely to do the job well.
Being a conformist by nature, my child did end up trying school for one term in Y5, just to see whether they were missing out. At school there were things they liked and things they disliked, some of which surprised me, but on balance they preferred home ed and came out again. Trying school as an older child was a valuable and interesting experience which IMO helped them to take ownership of their education and life; you know, in response to "Why are you home educated?" they had previously said, "My parents thought it was best because xyz", whereas now they could respond "I've tried both and here's why I chose HE."
I feel this was a better age for them to try school than four. Their sense of self was well formed, so they had a good perspective on it and didn't take things personally. So despite being a conformist, they had the confidence to think, "It's true that at this school only boys usually play football at break, and only people who are already good at it will have a go, but I want to play too and I'll stick up for my right to do so." They were old enough to cope easily with the things little kids struggle with: sitting still, asking for help when they needed it and waiting when the teacher was busy, putting on hold their need to use the toilet or eat or dance.
But I wouldn't extend that to say that ALL kids need to try school. Some children can see at a glance that school wouldn't appeal to them, and they don't have to try it just to prove a point. I was relieved that my younger child never wanted to try school. I think she would have learned things I didn't want her to learn: that her worth was determined by her ability to read and write, that wanting to play with dolls as a preteen is shameful, that her opinions and needs don't matter. She has a learning disability and is a happy, well-adjusted teenager, largely as a result of being able to do whatever was right for her rather than what might have suited the average chid of her age.