[rcxdude]

keeping information for the purposes of enforcing rules and bans is explicitly allowed in GDPR and you are not forced to delete it. (similarly, you can't ask a company to delete all the stuff you've bought and sold them from their accounts)

[londons_explore]

However many companies are sufficiently scared of the GDPR and potentially keeping data they shouldn't accidentally that they will just delete everything about you. You can totally use that to get the 'new customer discount' again at Uber for example...