Websites are usually private property. The owner can reassign any names they want.
I'm sure there are some accounts which appear inactive - but have the user regularly logging in an performing invisible actions like upvoting, private messaging etc. I would not expect those accounts to be recycled.
I would be shocked if something as mundane as that would be the top of any sane person's worries after reading the average ToS (and actually understanding it).
They often already claim ownership over every single byte you send them, disavow any responsibility for their actions, and in the cases where local laws force them to be responsible, will force arbitration on you. Half of my digital life would be lost right now if I did a $1 chargeback against Google and there is literally nothing I could do about it aside from proactive things like leaving their platform beforehand.
It's strange that you link to these articles to somehow justify the shitty thing you did, and they're straight out saying that you should _not_ be doing what you're doing.
The first paragraph of your post... "I quite often sign up to things just to snag the name."
GitHub:
"GitHub account name squatting is prohibited."
Telegram:
"we reserve the right to recall usernames assigned to unused bots and channels, as well as openly squatted usernames"
NPM:
"Don't squat on package names, user names or organization names."
I'm sure there are some accounts which appear inactive - but have the user regularly logging in an performing invisible actions like upvoting, private messaging etc. I would not expect those accounts to be recycled.