I think what you suggest is definitely possible, but my view is that anyone who would be influenced in this manner wasn't worth anything in the long run anyways so nothing of value was lost. If you don't have enough passion for what you're making and can be swayed by fads to this degree (assuming you weren't itching to make a game in a genre like that but couldn't up to that point, which can also happen) then you likely weren't gonna make anything worth playing had the fad not occurred either way.
Nice words and all, but a lot of pretty big companies and a lot of money gets swayed by these fads and I think it can have a pretty big effect on the game industry at large. The passion of the developers matter not when the big money chasing corpo overlords get the final say. EA has done plenty of whacky things in pursuit of trends. Like Dead Space getting led down a silly path with sequels. I remember there was some sort of cancelled single player Star Wars game at EA as well.
I mean sure you can just say EA isn't worth shit, but damn that's a lot of money and talent going into stupid places.
The pursuit of live services has fucked more than a few beloved brands and companies in the past decade.
Aren't all those shooters though? I generally don't play those so I'm not all that aware but basically how I see it is one shooter is always the big one, back in the day it was the halo series, then CoD, now fortnite. You always had some other stuff like medal of honor and battlefield and titanfall and overwatch and so on too, so I guess if you're saying those are the ones being done in I get what you mean, but I don't really think that is the case. It's just the stuff Epic would be making, other devs like bungie with Destiny 2 and whoever makes Overwatch 2 still make shooters don't they.
Grouping all shooters together would be simplifying things a bit. And just like you said earlier on how something like Fortnite is pulling in a totally different crowd, it's not really appealing to the players that would play something like Unreal Tournament.
I personally think nothing of value was lost with Paragon, I tried it and it was a janky ass mess from art direction to gameplay. But it was mostly a weird experimental MOBA. But well, it did have a fanbase of sorts and maybe something could've been done with it.
The original Fortnite was some sort of coop zombie survival crafting thing. I guess there are other games that fit the mold these days(though nothing on the AAA scale that I know). But there was an early access buy in, and there was definitely a fanbase looking forward to the original Fortnite.
Unreal Tournament was meant to harken back to the days of arena shooters(90s/2000s) and mods. The way it was advertised anyway was that it the developers were going to work closely with modders and whatnot. Community dedicated servers rather than matchmaking. A game that could be played however you wanted to play it. In a world where all multiplayer games are under the yoke of the developers/publishers who decide how the players should play their game, this could've been a nice return to form. But alas.
But maybe not all is lost. Halo Infinite managed to launch its Forge mode as cursed as the game is, and it has led to an influx of crazy custom modes and fan maps. The whole arena shooter genre has been on shaky ground anyway I suppose, so it's hard to say if it would've worked out even if they didn't have the success of Fortnite. But I think I'd like to have seen it taken far enough that enough of a community could've formed and then just kept it going or something even if Epic themselves decided to neglect it later on.
And going back to how you referred to how one big shooter replaces the previous one - like how there was Halo, then CoD, then Fortnite etc. In a way fans of Halo were totally left out to dry with the coming of CoD. I think this is a case of CoD actually getting a whole new market, but Halo was then helmed by a new studio which attempted to chase CoD's tail about the place. Which led to Halo fans having suffered over a decade, and are still suffering. The existence of the big new things these days can affect market diversity, so I can't really blame people for having some kind of resentment towards new trends even if it ain't the most productive thing to do.