As a dev though, I also understand the frustration. Creating startups is already time-intensive and stressful. A lot of us are on shoestring budgets. Most startups will fail. To a solo developer in the US, the idea of spending time understanding and complying with GDPR is daunting, it's more than just a hindrance to many. Still, I don't want to break European law, so maybe it's easier to block EU users at first and change policies later if profitable.
I think blocking is at least showing you respect the law, compared to just doing nothing and being non compliant.