I see a similtar situation with Ottomans: all turks minor allied with Mamlucks, QQ or Timurids; Serbia start with fort and capital (if they ally with Byz you must siege 5 provincies with fort or capital). Nothing of impossible, but the first wars seems to request more time/manpower.
In my first observer game Ottos lost first war to Hungary, Serbia and Byz and conquer Constantinople only in 1479.
Russia couldn't conquer Novgorod because of PLC. In 1487 it has lower income than Lithuania. And, well, AI took economic ideas and started blobing into steppe. By 1503 it had nearly same income as Poland (Poland had 2 more ducats) and was able to convert some lands due to luck bonus (but had only 75% of religious unity). Novgorod ate Livonian Order. And, in 1522, Muscovy attacked Novgorod. Do you think that fighting 72 income with 27 is bad idea? Totally wrong. Russia White Peaced PLC first and, then, after occupying whole Novgorod, and demanded to break alliance with PLC. No territorial gains, no manpower, 4 loans (1k total) - fiiinee... In 1531 Commonwealth appeared on the map. Ryazan allied Ottomans. Muscovy allied Ottomans *facepalm*. Commonwealth conquered half of Bohemia. It is 3rd richest country in the world after France and Ottomans. Aragon under Castile has more income than Muscovy. For some reason, Muscovy isn't great power while having 466 development. Persia is on the 8th place with 358 development XD