Transaction confirmation speed depends largely on how much hashpower is mining bitcoin, at a predefined "difficulty" that adjusts itself about every 2 weeks based on the current hashpower. If large numbers of miners suddenly go offline, global hashpower does down, but the difficulty stays the same, so what happens is it will take longer for the network to mine new blocks, so even high-fee transactions end up waiting a long time for the next block to be mined.

But in a normal, healthy network, then yes, what you said is true.


Probably because they mine blocks much faster than Bitcoin's network.