Because once they have your email and can link it to your identity via your purchase details they’re going to sell that list to some marketer sleazeball and you’ll get spam from other sources until the end of time?

“you’ll get spam from other sources until the end of time?”

So … ops normal?

I've signed up for plenty of these lists with per-site emails, and it's very rare for me to end up getting email from anyone but the list I signed up for. Might be different when shopping on international sites (though I doubt it's worse in the EU), but in the US, sites generally don't sell your email. More likely they'll leak it accidentally.

My email has been out there for 25+ years now. Filtering has been able to handle it for all but the first couple of years of that period.