Sure, but "Tumblr is not easy to use" doesn't really instill confidence. Tumblr used to be very easy to user. Perhaps one of the easiest websites out there in terms of usage.

The underlying problem is actually two fold:

1. They didn't understand their own customers need (which was, to be frank, share porn) 2. That they quite simply lost momentum

The first one is addressable. Just say you're going to allow porn again. The second one... Well, that's harder to address.