Certain melee combinations can work really well if they have great harass or, more likely, killing power. Versus lanes with ranged heroes you're going to get harassed and denied a lot, so either you can have to quickly notch up a level advantage through kills, or you're going to be ground down and forced away from farming.
Losing a lane like this is really bad for the team - not only are you and your partner underfarmed, but the enemy has probably been able to fill their boots. This sets you up badly for the whole game, and it can be a long way back.
So please, the next time you're looking at picking a melee hero, just make sure there's somewhere good for you to lane:
- You can jungle if appropriate (and your team has a solo)
- Some mid melees work well
- You have a ranged carry in the safe lane and can pick a melee support
- You have a great combo with another melee hero and can lane with them