In what cases are they mandatory? I've been leaving them blank for decades.

FreeDOS has no accounts. Neither hasn't Haiku, nor Amiga. And any OS from 8 and 16 microcomputers with FPGA's have no concept of that either and if they can run Frotz they can for sure play Interstatal Zero, (I-0.z5), both in English and a faithful Spanish translation (Interstatal Cero). Oh, you are now able to run a 18+ game even under a PSP, a PDA, an old phone with no concept of accounts at all (J2ME interpreter), classic Mac's, a Post Script file and even FreeDOS.

Go try implementing accounts under FreeDOS or CP/M.

Now potentially a 18+ game can be showed to billions of native (and non-native) English speakers from nearly any OS sice 1979, even under a PostScript file (zmachine.ps), albeit it needs to be extended.

This law it's idiotic and it shows. Will they ban retrocomputing with Amiga OS 3.1 running on FPGA's or what? They can run the modern web with TLS 1.2/3 with AmiSSL. They can run IRC against Bitlbee and login into Steam, Jabber, Discord and Mastodon with relative ease. Gemini can access most JS-less webs at gemini://gemi.dev and Gopher clients for sure it might be some adult content referenced at gopher://magical.fish and gopher://sdf.org, even if it's just mildly NSFW, such as harsh language and sex references. The Javascript-less web, too. Usenet, more adult discussions and content, maybe with heated flame wars. And for sure they can run Frotz with that mentioned game game, at full speeds.