If you're a paying (every month, no soliciting, ahead-of-time) tenant and a landlord is raising rent at all: they run the risk of losing a known quantity for a piece of shit tenant.

Unless you're in a usurious, fucked up market (San Francisco), rental owners need to put a dollar amount on losing your tenancy.

If you're paying $2000 a month, raising the rent 5% means that, for an extra $1000 (potentially), you'll spend your time and money showing, placing ads, screening prospective tenants. Time is money. Either you're doing this yourself, as an owner, or paying someone to do it.

The other cost factor at work applies to the tenant: the "cost to move." It's hard to move in-town for less than $500, so this must be weighed.