i mean. obviously not, you can do whatever you want, but imo just because you can go plotless doesn't mean it's the best idea for the site.

whether or not it's a good idea though... honestly, i think it more depends on the general vibe and the actual site itself.

by that i mean - some sites do really well being largely plotless slice-of-life sandboxes (like i think ccr/ct really thrived as a basic "open world supernatural sandbox" and imo 99% of all the real life city/town sites follow this exact format). others don't (like i personally don't think the typical route-based pokemon site lends itself well to the plotless aspect).

a lot of it depends on how wide the setting is - after all, it's a lot easier to get away with no plot if you're in a setting where the scope is very limited and it's easy to get connections with people without relying on that plot to get movement (aka it's a lot harder to go plotless in a site with four kingdoms and no one really travels outside their kingdom for no reason since oops no plot generally means no reason for most characters). but another important factor is also member interest - after all, if i have a harry potter site where the death eaters are coming back, imo, if i don't have any death eaters and no one's really acknowledging that plotline, it's not as if it really matters in the grand scheme of things and trying to force it is only going to end in staff frustration (but by the same token, if you have a lot of apps using this as part of their character concept, it's gonna be a big pain to try to remove that plotline without causing other issues).

honestly, i actually tend to think of things less as "plot or no plot" and more "plot vs premise vs plotless". it's a bit easier for me since it lets me make the distinction between essentially "atla site where we have to defeat the fire lord and are going to be taking steps to play this out" vs "atla site set in a baby republic city where we have the new ozai society threatening peace but this status quo ultimately isn't going to be challenged in a meaningful way on site since it's more a backdrop than a situation we want to resolve" vs "atla site set following the end of the 100 year war where we're working out peace and are largely an open sandbox for you to play in".

i typically tend to favor the latter two more than the former but personally, i'm more drawn to what works well with the vibe of the site + what the setting can offer than i am anything else. if there's enough to work with in a setting to go plotless and not struggle for players to interact (or for those interactions to get stale p fast), plotless is good; if not, having a premise will help people with getting started. but personal preference does also play a factor (ie, i personally find the overarching hp world interesting enough to vibe in as a general thing but some people prefer to have some kind of plot or premise to give it some direction), so y'know, you kind of have to go in the direction you want to go in and hope that your memberbase follows suit.

now to nervously sweat because i posted this from a phone so who knows if it makes sense + is making all the points i wanted to with this asdfjkl

I think there's a difference between "having a plot" and having a plot. In a lot of sites that present as having a plot, it's just a dose of spice layered on a setting. My personal classifications are:

Setting only - Here's a place, and that's it. Lore, if any, remains static. 

Setting with a plot / premise: Here's a place, but with superpowers / groups / different character types / hook of your choice. None of the dynamics presented meaningfully change since they're mostly there for flavor, so lore remains mostly static. 

Plot-driven: Things happen that do impact the canon of the site. My definition of what it means to have a plot.

I've always by definition put slice-of-life rps in the Setting Only category, if that answers your question. There are also rps in the second camp that I still consider slice-of-life in practice if dynamics never change.