I'm fine with that if they're providing value to be there. Let's use Primal as an example. If they adopted an ad marketplace where they would allow inserted ads to be sold to top bidders of attention. They'd drop the advert in and collect the funds within their platform while hopefully also distributing it out to creators and maybe even the users that curated through their likes on primal's client or even attention tracking software deployed within primal apps for general users that scrolled past viewing a particular ad. This wouldn't affect the wider nostr ecosystem though the wider nostr ecosystem may still benefit through a curators reward program Primal could deploy funds to reward top creators that's content is viewed within their platform by simply zapping or NUTing creators regardless of the platform used.
Now that's nothing like replyguy who's not providing any value for being there and also spamming relay providers with unneeded events to take advantage of early notification systems with ads. The ad content may be the same message quality but as the user base grows so too will the advertising base. Eventually scammy ads will likely be priced out or if not at least highly reward the ecosystem's GDP.
Just like X does you could also make a benefit of Primal Premium be less or no ads and then share a portion of the user's subscription revenue to the creators fund. My point is I have no problem sharing the value of my attention with the nostr ecosystem or ponying up some sats for an ad free version of it helps to reward client creators, DVM ecosystem, nostr creators and the users themselves.