You can "root cause" to any depth. The trick is to stop at some point that is fixable.

If the thing is broken because X then you can fix it by removing X. That's enough explanation. You don't need to know "why" for everything.

Sounds like there was something wrong (at a hardware level) with the network card, so the real fix would be to buy a replacement.

But if disabling a faulty connection you don't need in the first place stops the problem happening, that's a decent workaround... I'd just be a little worried that something else could be faulty on the card if the WoL pin is glitching, so potentially you could have other intermittent issues.