Why should Frank have primacy over Joe? Joe was there first. Should it simply be because Frank has more money? That's a pretty terrible way to decide these things. I mean, at what point do we say that Frank deserves Joe's other things simply because he has more money?
Basically, you're just making a "Might makes right" argument, but substituting wealth for physical might.
Why should the owner of the building have to lease the unit to Joe at a lower cost than he could rent it to Frank? (Joe and Frank are otherwise equivalent as stipulated by GP.)
Do I have to sell my labor to my current employer cheaper than a prospective new employer? Do I have to sell my used car cheaper to someone who once rode in it than I could to another buyer? Why then should landlords be subject to those restrictions?
Because housing instability creates social harm. Tech salaries would (probably!) keep pace with the demand for non-rent controlled San Francisco housing, but teachers, cops, firefighters -- let alone retirees -- incomes won't likewise scale. Folks like that will be rapidly priced out of living anywhere for longer than the length of a minimal-term lease.
A stable community is a thing not much valued by (young and transient) tech workers, though I would argue that even they derive some benefit from living near folks who make less money than they do.
Rent control doesn't create utopia -- and this article describes some of its acknowledged problems -- but neither would abolishing it be free of consequence.
Like most things in life, it's a trade-off. Don't overlook one side of the exchange.
Basically, you're just making a "Might makes right" argument, but substituting wealth for physical might.