If you know what you are doing it isn’t a huge issue.

But enclosures generally provide the following benefits either by design or as knock ons:

1. Temperature control. A heated bed or even chamber is obviously the optimal but even just having a big ass bag over there catching all the heat of the printhead goes a long way towards preventing rapid cooling of layers and all the impacts of that.
2. Filament guiding/management. A shockingly common issue is that a rapidly moving printhead can increase kinking in the filament or even back feeding and “tangles”. Most enclosure systems come with some form of a bowden tube rig which helps a lot for that as the filament says mostly “stable” as the printhead moves
3. This is less of a “guarantee”, but a lot of the enclosed printers also come with a camera of some form. Which helps a lot for when people suddenly get confident enough that they don’t immediately run to their printer at the start of every print and minimizes the “My entire printer is now a blob of ABS. How do I fix that?” posts.
4. And… honestly? Bed slingers haven’t really advanced all that much in years. You can buy a brand new printer but it is still an Ender 3 (which I think is actually a Prusa something or another?) whether you bought that in 2015 or 2025. Whereas Core XY (and the few enclosed ender 3s that aren’t just a tent) actually has had a good amount of R&D and starts to highlight the differences between companies.

I am not saying people should throw out their printers and get a new one (although I did late last year but that is more becuase I hate anycubic with a passion. Qidi Q1 Pro is shockingly nice). But if you are buying a new printer and looking at like a 200 dollar difference between a rebranded ender 3 and an enclosed core xy? I would very much say to think that through. ESPECIALLY if you aren’t planning to heavily mod your printer (also if said mods are to basically provide the same functionality).

And for a newbie who doesn’t really have the built up skills and Opinions? There is a lot to say about being all but guaranteed a solid benchie and califlower right out of the box.

Enclosure makes printing some plastics much easier/safer, and it’s become common/inexpensive enough to be a “default” option, especially with options like the Carbon being so affordable.

But the tool has to fit its purpose. If you only print PLA/PETG, then it’s not really necessary. I mostly leave the door off my printer, and only attach it when I need to print ASA or ABS.