It's a wonderful medium but has it's downsides. Learning curve is there because people are not that familiar with board game mechanics, personally I have bunch of experience in video games and board games and whenever I play some new board game it's just familiar mechanics but arranged differently and thus it's easy to pick it up.

But every person is different and often learning a new board game is like learning entirely new medium. Also 30 minutes to explain rules is on the light side, some games require an hour and some playthrough. Also people often lack the patience to learn. Last board game I got had bunch of different elements, like deck building, area control, worker placement, set collection, and probably something else I forgot. Essentially you have loads of options and need to find most optimal way to get points. Mid rule explanation others decided they want to learn it on the go, did not fully grasp game mechanics and complained that they do not get it.

Getting a group together can also be quite difficult, specific groups need specific games and as someone who likes heavy games face more difficulties there. Oh and set up can be a torture. But once in a while it's possible to overcome every hurdle and have an amazing experience that overshadows everything else.