You wouldn't have gotten 100 merit based on a few days. If you had joined ~60 days earlier, then you might've gotten 10 merit.

I acknowledge that it is in some sense unfair when people missed out on a lot of free merit even though they were very close to rank-up. I considered several methods of progressive merit distribution that would've addressed this, but I felt that it'd always end up giving far more merit to people who didn't deserve it than people who did, so I kept the distribution to just the minimum required to avoid demotions.