The problem with landlords is inherent to landlords and not specific to large ones. If your BIL owns three houses in a well off area he is a wealthy landlord and I seriously do not want to hear that type of person claim "woe is me"
Idk want to derail the thread because addressing the very dumb progressive idea that cracking down on short term rentals(STRs) will fix the housing crisis is very important but if you're interested look into Georgism and specifically
this article which summarizes the position. If you want an even shorter summary of the problem with landlords there's this satirical billboard from the early 20th century that succinctly makes the point
As for this cockamamie idea that the problem is because we have too many STRs, I wholly reject this. The issue in Canada is NIMBYism and specifically their terrible idea of
Vancouverism whereby the only type of multifamily housing allowed are towering skyscrapers concentrated in the city center and the rest of the city's residential land is locked up in single family homes by NIMBYs who refuse to allow more housing to be built. Crack down on them by forcing these neighborhoods to allow more dense, affordable housing instead of governing the country in the interest of Boomer homeowners.