For one, it's against every rental agreement I've ever signed (no subletting clause). Another reason people don't like it is due to the party people who frequently rent these, the extra parking spaces being used, people moving around at all hours, people not caring about the space because they don't own it, etc. Basically all the things which are incentivized in normal multi-month rental contracts which are not present in Airbnb contracts. People who live in an apartment building don't want a hotel room next to them.