I think there are some legit arguments for why Matthews might not win the Hart. But the arguments trotted out by un-objective haters (like these) are just comically bad.
If you want to judge Matthews' defence, look at the outcomes he can actually control. Like scoring chances or expected goals against. In looking at those metrics, he's actually one of the best Leafs forwards (behind only their shutdown line players). Unless your argument is that Matthews is personally coaching Campbell/Mrazek/Kallgren to let in hilariously terrible goals, the goals against argument just holds absolutely no water.
I also don't get why people are trying to poo-poo some of these feats he could achieve. Like "oh, it's not a true 50 in 50". This is something that hasn't been done in decades. It's clearly special. It's something most people thought simply wouldn't be possible in the modern era.
He's been a terrific player this season. Should he win? I say probably, but at the very least he should be in the mix. Some of these attempts to knock him down are just pathetic though.