It just seems like if you get 10 first from taking down a fort or something and you don't force a team fight/get some picks to secure more objectives on the map/get more ahead then you are asking to be behind in exp late game once they get your forts down too.

Nah. It's over when 4-5 level difference because they literally breached everywhere and 1 lane to core is open.

Feeding isn't that much of an issue early game.

feed early and you give other team their ults first. If other team is smart they will force a fight at that point IE over map objectives or just all shove 1 lane so you either have to let the fort fall or engage.

If you have your ults first you should always win these fights..meaning you just get more ahead.

The only reason why feeding wouldn't be much of an issue early game is because it typically comes down to making 1 mistake lategame that will cost your team the win.

Feeding isn't that much of an issue because if you soak more exp on other lanes you still get ults first.

You are also talking about the normal 0-3 level Scenario in HL.

When they got 4-5 level difference you can surrender because your core is wide open. That's a <10-15 minute game mostly named Quickmatch or a single Queue HL, with carried noobs.
That usually happens when they go 4-1-0 and it's pretty difficult to stall your lane with 4-1/2 once. It's more important not to lose the towers and the fort early on.