I really don't see any issue with them using Unity
Has been proven to be severely problematic when used for massively (emphasis on massively) online games time and time again, version improvements notwithstanding. And it's problematic in a number of aspects, plural.
Now i assume it's possible
someone could be the first in the planet to code from scratch an efficient 100% serviceable module that handles the 'online' aspect just fine; but at the danger of being pedantic, i'd ask you to calculate how statistically possible this is, given that:
i) The "spearheader" of the technical aspects, all of them, is a farmer from Bahrain.
ii) that said farmer, all by his lonesome, will manage to do what no one else, ever, has managed to.
It's easy, it's mainstreamed to bits, it's "free"; ish. I get that.
Many things are "free" in life; sadly most of them just aren't capable of fulfilling all needs.
Building on the above fact, this part feel free to ignore, we've reached a state where no one does anything, no one really knows anything. Meta on meta. Ready-made tools designed for the many are by definintion not the optimal ones to use for something so niche. Expand this further and consider just how the fuck a Star Stable dev, a no one and a Twitch Partner could possibly, ever, do something so complex right; correct, they couldn't. But they can play with tools made by others (who
do know) and thus "do".
I won't dare coin this as intellectual debt, it's a gaem of all things, but.. the Meta factor stands. These people saw shit on youtube and think they 'know'. They know fuck all.
I'm also very wary of people with random, unrelated or straight out decline jobs promising me 'old school'. Very wary of that.
I'd need some serious demo to be convinced this is the exception to the rule.
* the Meta factor stands for the gaemrzzz too, the younger gens thinking they 'know' or 'want' it old school, until they sub to the likes of EQ or Vanguard; and fuck right off again, but that's a different subject. Pure opinion this, like i said ignore it, but i don't get an "age" impression here, talking about the devs again; i get "young" (pretty colours, very well lit everything, no forum at all, but sure we've discord and streams, twitching, etc); ergo as i said above, Meta