Well, to be blunt is say you've been a consumer of SO. There's nothing wrong with this but I'd argue that if you don't have 15 rep after 4 years you've been paid back with the knowledge you've gained.

If you can't find a way to get 50 rep on SO get 200 on any other exchange site and that will credit you 100

Have you been engaging in actions that potentially earn you reputation points, e.g., editing or answering questions? If not, that's why. If you have, but your contributions have gone unrewarded, that's an SO problem.

I was a member and daily reader of HN for years before I started participating. You don't get down vote capabilities here until a much higher point threshold, and I think it helps. I think it's more likely to cause you to conform a bit to the community rather than clash with or disrupt it.

You see it here occasionally, where someone is getting down voted and they don't know why, and someone will explain its most likely because they aren't acting within community norms (here it's back up factual assertions with sources, keep it civil, if you make a joke keep it topical or follow it up with something useful, don't just post memes, etc. Basically keep the signal to noise high).

Limiting new users for a while when their initial mode of interaction may not fit will with the site is a sane choice, IMO, and if those new users never make the effort to go past that initial hurdle, it may be that their contributions are high enough risk that it's not worth it (or the hurdle could be too high).