Your counter to my argument would only hold if the developers making sims in the late 90s were still making them now.
The only one is ED, that's it. All the others making them now started after the market crash. All the big ones from before that?
EA/Origin?
SpecHolo/MPS?
DID?
DI?
Whoever it was that made Jetfighter (I played 1-3)?
Dynamix/Sierra?
Razorworks?
Microsoft?
I know I'm forgetting some others, there were just so many back then.
I don't count Ubi because they only published Russian-made sims from what I recall, they never had any in-house developers of sims or even any Western ones.
All of them either just quit making them/folded, or first released lame attempts to "broaden" the appeal that sold worse and resulted in them quitting/folding. In fact other than EA (but not Origin), none of those others lasted past the middle of the last decade even making OTHER things. They knew how to make sims, and their attempts to do more only killed off their existing customer base and got few or no new ones.
Take MPS. Both it and SH made tons of sims in the early/mid 90s, then merged. Then came the Hasbro buyout, and after Falcon 4 we got Gunship! (with a ! yet) and B-17 II which had its MP stripped out. While both of those sims got modded in later years, they were mega flops at release because they alienated the core while failing to appeal to a larger, different crowd. Larry Holland of SWOTL fame made the craptastic Secret Weapons Over Normandy and then blamed the simmers for not buying it because it wasn't "accurate enough" for them (totally avoiding the fact that the genre it was meant to compete with, Ace Combat and the like, blew it away in quality).
MS is of course making their return but in an as-yet unproven direction. I don't care about it (as I never cared for MSFS), but I'm interested to see how it sells compared to FSX. Will a total revamp garner them more sales? Or will it still fail to interest the non-simmers while alienating the simmers? That's the historical pattern.