the bit about start dates has some relevance to it, but not for the reason priest and OP think.
I would surmise more serious players - including f2p - rack up not only more opportunities to open voids through efficient grinding, but put them to much better use.
Collect void shards, save void shards, open as efficiently as possible. The rates are the rates, can't argue that, but 1% is certainly better than 0.5%.
Mostly I just go into mercy, but occasionally sneak an extra void leggo before that.