There are two strands to the argument I think.
1) Can we understand why the club did it? I've tried to outline this and set out some parallels. You can agree with it or not but too many of our fans (not so much on here) view every season in isolation which is just stupid. We didn't buy Fabio Silva so he could fire us to the Champions League in 2020/21, no-one thought that. We'll see how it goes.
2) Is he ready now? You would have to say no. Is this doing him any good? I would say it probably is. I have no idea where his ceiling is but if you want a bit of tough love then having to face top end centre halves every week in a struggling team, it'll make you a man quicker than you think. Eons and eons and eons down the pyramid but I remember me at 18 going into men's football, I didn't have a prayer when I first started (but I could play a bit). By the time I was 20 I was up for the scrap. People develop at different rates physically, we'll see how we go. 18 is very very young indeed.
I think to write him off is disrespectful and short sighted, at best what do you get out of it? In five years you get to say "I was right" in a conversation no-one remembers? Well great.
We all want the best for him, surely.