>stuck paying someone else's mortgage.
What he meant was that when someone is not paying the rent, and you are evicting them, you are paying for the living expenses for a stranger who may holding your property hostage, who may be actively abusing the property, who may be deliberately prolonging the experience.
This does not feel good to pay out of your own pocket to shelter someone else's family for any amount of time. There is no recourse to recover the money. Your best outcome it to just get the property back as soon as possible, even if that means rewarding the bad tenant with more money. And in most places in the US now, evictions are not even possible due to virus lockdowns.
Not paying rent is theft. It hurts financially and emotionally when people steal from you.
And for the soft-hearted landlords who didn't screen properly, or took a chance on a sob-story, it was already months of slow-pay or no-pay before you started the eviction. Can you imagine someone stealing 4-6mo of living expenses from you?