those crazy users, not wanting to install, configure and update software, download their emails and make sure their backups work, and just get on with actually reading their emails on whatever computer they wanted
Those crazy users who then cry, "what do you mean I've lost 10 years of e-mails forever, becuase my daugher commented with an emoji on a YouTube livestream, and Google decided to go nuclear everything associated with that account?".
Cloud services aren't more reliable than owning your data. They're just unreliable in a different way. You need backups anyway.
I'm of course referring to the Markiplier drama of last year, where a streamer asked people to vote on his stream by typing in red/green emojis. This resulted in hundreds of people losing their Google accounts due to an oversensitive spam filter. The matter fortunately got sorted out (somewhat, not all accounts were unbanned), but essentially only because it involved a fairly well-known youtuber.
And random automated bans (which happen on all big social networks) are only one fairly common failure mode of cloud services. Smaller services shut down or get acquired, taking your data with them, or they just shutter the products you depended on (and even if you can export data, there often isn't anything you can import that data back into). Governments may randomly make whole populations lose access to service (c.f. Adobe's Creative Suite and trade sanctions on Venezuela, earlier this year). And, of course, no Internet access = no access to service = no access to data.
In general, owning your data makes you vulnerable to physical world problems - floods, fires, etc. Using cloud services makes you vulnerable to relationships between you and third parties, as well as between these third parties themselves.
Server side email has the failure mode of the company going broke or banning you. Client side email has failure modes like destruction of device (house fire, flood, other accidents) or even just obsoleting of OS/app. Neither is inherently superior to the other.
In the particular case of the emoji ban, the problem is that the FTC should never have allowed one company to control search AND email AND school document sharing AND maps/reviews AND video AND mobile phones, etc. If you don't use Google for your email, there's no danger of Google banning you from it. :-) More seriously, Google (and Amazon and Facebook and Microsoft+Github) needs to be broken up to protect consumers from one company having a chokehold on their digital lives.
Cloud services aren't more reliable than owning your data. They're just unreliable in a different way. You need backups anyway.