Yeah this causes "fatbergs" which wreak havoc on city pipes. I get frustrated when I see memes like this condoning willful property damage bc not only is it stupid and it hurts other people besides the landlord, but even if the landlord has to shoulder costly repairs for plumbing inside their unit, they're definitely going to pass those costs on to their tenants (either immediately or over time) so this could also contribute to rent hikes.