I don't know this perfectly, but I can kinda fill in some of the gaps that might not make sense.
The ranked system is designed to create the most consequential differences between people of similar rank. It wants people to play as many others as humanly possible, but realizes a system that punishes players of a higher rank for playing with lower ranks will simply cause selfish high-ranked players to avoid playing with lower players at all costs. Thus, it creates a low-risk situation for someone with a high-rank, while giving a low-risk, high-reward situation to lower-ranked players. It gives the reward to the superior fighters in the form of a streak bonus, which starts negligible but I want to say caps a little under half the gains of a similarly ranked player.
If the intent was to make it so that players should want to play as many others as possible, it would have worked if it explained itself. Your best way to get a high level is thus to crush as many people as humanly possible. And if you are a low-ranked player, it's probably in your best interest not to fight players of a rank significantly higher than you (maintaining streak is a more consistent means of going up the ladder rather than risking it on decent players), but that's counter-intuitive. In the end, the result favors players who get into as many matches as possible rather than those that look for ideal settings.