I fear too many simply do not understand the concept of classic computing and so "fail" to "self-host" simply because they try to reproduce a cloud service provider infra they do not need at home.
Personally I know few colleagues enthusiasts to have Proxmox set up at home and all of them fails to say why they need it. Similarly few "geeks" enthusiasts of their new toy no matter what, it's a "Widows classic" race toward colorful WebUI without asking if it's needed, useful or not.
Just as a small example: even a personal, small, static, clean, classic website, why not just making with a homepage saying "this website is just the advertisement of my feeds, there are same random post as showcase, if you like them just add this or this other feed to you favorite feed reader, full articles are in the feed, no ads or so". If the website is just a kind of blog that does not sell products, live on ads etc why maintain it at all will all classic web things?
Similarly why webmails? We completely miss modern MUA, yes, because all development is centered around web(cr)apps, but some for geeks/techies do exists (for instance notmuch, mu) and a frontend for generic user is not that strange (some exists, like astroid, but are not much nice probably because too few develop and use them) "hey but that means downloading their own emails!", yes. Emails are actually personal data no different than photos or pdf why consider them something else?
Long story short: why invest FLOSS development time and resources to copycat big tech tools built to lock-in and control users, not for users advantage when we can know from the history, just looking for it, how desktop computing was born, networked and so powerful?
A personal romance description: when I power on my desktop I hit a button and do something else while it boot (for instance taking a shower, eat something, get dressed, ...) it boot up with an "agenda view", witch means a sort of timeline and tasklist combined. A single key on my keyboard open a search & narrow UI for my personal data, anything, I can type first chars of a person name, get a pertinent result instantly, see the relative "card" with links to email exchanged with that person, specific threads I highlight, things we do together, things we have up/todo etc in a single "active" page. But also cards for my phone bills well ordered in timeline, with matching bank transactions, notes, notification mails, ... But also cards for ideas/projects, personal notes, investments, tools, ... My dishwasher break? Ok, a single key, few chars, enter/tab and I'm in it's card with info about where, when I bought it, relevant model, vendor, ... so in an instant I have all info I need to call someone for an warranty intervention or that's out of warranty etc. It's a magic web-app self-hosted on k8s home cluster run on two servers etc? No. It Emacs/org-mode/org-roam/EXWM/* and few bits of elisp and script to automate workflows enough. Easy to sync on all my machine via my simple homeserver with unison, no webui needed, from remote it's just fwknop+ssh just to be paranoid and get far more safety than a complex web auth with OTP, perhaps on crappy and full of vulnerabilities "smartphone" etc. Yes, collaboration is not so immediate, but just because Emacs community is not big enough, so certain aspects are not really developed and if you look around real collaboration is actually not really developed anywhere, for most that means a shared repo if you are a dev/ops guy or a shared "directory" to push&pull files from with some kind of extras almost ignored by 99% of users + some softphones. We have screen sharing, also good enough with certain apps, we have even near-real-time multi-users simultaneous edit of generic documents, almost no one use that feature. We just still have to learn how to push data/files around to really collaborate.
Since from the Xerox Star Office System (not to be confused with proprietary LibreOffice predecessor) years have passed it's about time to resolve such issues instead of keeping play with bloatware and anti-users tools...