Premades win worlds more often nowadays because the map is smaller.
Whether it be in old or new worlds, if a decent enough premade started in a continent, they were probably going to win it. There generally just isn't a strong enough player base within a single continent to oppose a top premade, whether it be talent or leadership ability. In older worlds that was fine, because there was over 50 other continents. On W60, my little outer-core K tribe was separated from the best premades by three to six continents. Yes, Valour which was the closest thing to Obey in W60 in the early game was nearly five times as big as SPAM, our tribe needed time to find its groove and for players to get battle toughened. This is what happens when your tribe doesn't consist of the best players plucked from other world winning tribes. We had to rely more on teamwork.
In newer worlds, if you win a core continent, you essentially get control of 1/4 of the world and are in the endgame unless your tribe implodes internally. This is what makes premades so powerful, they essentially guarantee you getting that continent whilst tribes led locally often don't have enough time to find their mojo. Those slow trudging wars that give players experience don't work on newer worlds because by that point Obey or whoever is over twice your size.
And yes it sucks in my opinion, I'm only in Obey because I like to be in good tribes and being in bad ones frustrates me. I also don't have the motivation to try found my own at the moment so Obey is the next best thing. Yes Obey are very likely to win, but unfortunately that's what the game has come to since it has become less popular leading to smaller worlds and P2W features that are far easier for more experienced players to abuse.