All I can say is that not everyone's situation is the same. If you have a small forum where a few hundred people post a few dozen messages a day, it obviously won't be a big deal. There are situations where the amount of generated information is much larger than that. Webserver logs are one possible example.

It isn't an impossible problem to solve, but the GDPR is a significant time and a money burden that will especially be an issue for small startups that don't have millions in venture funding to spend on this.