Surely the same could be said of nearly any network sitcom involving a subculture or demographic. That's kind of the idea of broad entertainment.

The problem comes when the parody comes at the expense of the culture - that's exploitation. But by the time BBT was airing and popular, nerds were, and remain, to a certain extent a privileged class, not an oppressed one. They have high-paying jobs, ordinary successful lives, and look back at the old stereotypes of pocket protectors and social awkwardness with a sort of bemusement. Nerds are not a vulnerable class and haven't been in a long time. Nor is "nerd culture" particularly cohesive.

That may not be the case when the group being parodied is genuinely being oppressed or discriminated against and is often not in a position to push back against that. Exploitation in that case can be real and harmful.