1) Maybe they don't have plans to do anything with it today, but they don't want to get locked into renting to a tenant for decades. That's not irrational.
2) No, that's not just pushing the problem back a bit. That is wrong. There will always be owners who want do do something with their property somewhere down the road. If you allow them to rent it out in the meantime (without getting locked into a forever contract) you can permanently increase the total rental stock in a community.
Owners may evict a tenant in an owner move in. There are a variety of regulations that you can get caught up in, designed to protect from abuse by commercial landlords, but practically speaking, if you own a single building and wish to evict rent controlled tenants live in one of the units, you'll be able to. Your objections continue to demonstrate an unfamiliarity with rent control in sf.
@harryh: your complaint is rent control prevents owners from renting out their property (while doing something in the meantime) without getting locking into a forever rental. For small landlords, it does not, at least not in this enumerated (most likely the most important) instance. As a small landlord, most importantly of a single unit, you may rent it out as you wish and move back in later, evicting a rent controlled tenant if necessary.
2) No, that's not just pushing the problem back a bit. That is wrong. There will always be owners who want do do something with their property somewhere down the road. If you allow them to rent it out in the meantime (without getting locked into a forever contract) you can permanently increase the total rental stock in a community.