If you're a German company serving mostly German users, but you have a single user in Portugal, and that single user files a complaint with the Portuguese authorities, bad news, they will investigate you and communicate with you in Portuguese, and you'll have to hire Portuguese-speaking legal counsel to deal with them.
And then you have a single user in Lithuania who decides to file to complaint. And then another one in Romania.
And so on.
You don't even have to have done anything wrong, you might be 100% GDPR-compliant, but that would be enough to possibly drive you out of business.