It‘s great. Also, if you take the piss out of them by asking stupid questions such as if the entire company can address you as Herr Frankfurt and speak to you only in Russian when it‘s a job in London they start removing you from lists. I went from 3-4 per day to 1-2 per week using this approach. It‘s also fun.

You can also delete all your employment history from LinkedIn. I can personally attest that it reduces spam from that to zero. Obviously save a copy first if you think you'll want it later.

The weird thing about LinkedIn is that it’s dependence for jobs is reducing (I can’t remember the last time an employer asked for LinkedIn) but it’s needed in the most unexpected scenarios. Recently a bank asked for my LinkedIn to open a company account. When I offered to send in a CV as I don’t have my employment history on LinkedIn, they stopped replying.

Too late?

It seems somehow they retrieved physical emails back in the day, before everyone removed their mails from LI. Now they're hitting mail directly but somehow still aware of your current LI profile.

I assume they have an aggregated DB connecting everyone's socials together with physical mails which they share or even sell to each other?

Bingo. And LinkedIn allows you to deactivate your account now, instead of deleting it. So you can keep it dormant and only reactivate when you actually do want to find a new job.