Camshaft wear

Hello, all. I'm working on this older Craftsman riding mower 917.272761 with a Briggs 31H777-0202-E1 Single cylinder engine. It runs smooth, but won't get up to speed, despite wide open throttle. It also cranks kind of hard. So I thought valve adjustment, maybe the gap is too wide and the compression release isn't actuating... What I find is the adjustments seem fine, but as I turn the engine slowly by hand, the exhaust valve is opening nicely, but the intake barely moves.
Is it likely for an intake lobe to wear that much more than the exhaust lobe, despite that it it lower in the engine, and therefore probably better lubricated? Or could this be due to a stuck compression release? It just seems weird to me that the intake would wear that much more than the exhaust. Or is there something else that might cause this? The push rod (aluminum) looks good, I even tried just holding the push rod by itself down the rod hole while turning the engine by hand and it still barely moves.
Anybody else run across this? Could it be something else, like a too short tappet? May or may not dig in, depends on if the owner is willing to pay. Any insight is appreciated.

Well it is a moot point
If the cam is worn then the engine needs to be split to replace it
If the Decompressor is failing you need to split the engine to replace it as well.

And yes.
From what comes into the workshop the intake cams do seem to suffer more wear.

Well, it's only a moot point if I pretty much covered all the bases in my description. And by your reply, I apparently had. So thank you for confirming my suspicions, and assuring me that the intake does indeed often wear faster than the exhaust. I do mostly service and maintenance, and don't get to really dig in too often, so I like to ask questions when I come across something new to me. So it was more for curiosity then for trying to figure out how to proceed, and for just in case I totally missed something.

The only thing is not to order any parts till the engine is split.
Most the clientelle will not pay for a case split

The only other thing that affects valve lash ( apart from actual valve & seat wear ) will be a guide shifting in the head but you should be familiar with that.