And by heavy we mean heavy-weight because you do all the work.
Well, to be fair, the Railroad and the Brotherhood are actually well-done in the aspect of
"you don't do all the work". The Brotherhood patrols actually show up everywhere, they provide assistance during main quests, and generally have a proper presence.
The Railroad has a functional and self-sustaining espionage network behind the scenes of everything, way before you even get involved. Old Man Stockton, Deacon showing up literally everywhere, plenty of civilians who you wouldn't know were either synths or agents before you joined the Railroad.
It's a somewhat organic system working behind the layers of the game, and while significantly inferior to New Vegas' approach, it was still pretty good for a Bethesda game.
Sure, you
still do most of the work for them, but that's only because of the theme-park power fantasy aspect. They needed to make the player feel like a hero no matter what the player does.
If you take that away and make the player character a balanced, realistic wild card like in New Vegas, then the Minutemen is really the only faction that would have zero power over anything. The Institute could continue using Kellogg and Coursers, the Railroad worked just fine with Deacon, Glory and the Heavy units.
And the Brotherhood seemed pretty alright on its own, with them handling the Mass Fusion quest on their own if you side against them. That was honestly a nice surprise and far more than anything I expected out of Bethesda.
So, all in all, if the entire game treated you less like a god amongst men, then the Minutemen would be the only useless and utterly pointless faction with no exposition or lore behind them.
How factions function on their own without your input in Fallout 4 is vastly superior to Fallout 3's approach. Bethesda definitely learned that from New Vegas. There's at least that, so quarter of a kudos to them I suppose?