If we think at a systems level there's a cohort of people (that will change over time) that are looking to plug their gambling ideology into anything that will accept them. This behavior existed long before bitcoin and will continue long after. We just need to make it prohibitively expensive to do this with bitcoin.

Initially proof of work was designed to mitigate spam and it worked thus far in bitcoin but I worry that as mining pools seek to earn more profit they'll find ways to promote these scams until the nodes thoroughly reject these transactions.

At least 44% of the hashrate belongs to a powerful and authoritarian government that demands censorship at all costs. They probably have significantly more. That government also effectively controls the vast majority of the supply of mining equipment. If they have over 50% of the hashrate they can sustain spam attacks indefinitely and thus create censorship via fees. These pools effectively raised taxes on all of us.