If you live in a state of believing that the market is actually fair and others have an equal shot at participating in it, then someone else entering the market in defiance of the existing protections appears to be unfair.
It's hard to believe that you didn't enter into a job market and win a wage fairly. That, instead, you were unfairly advantaged by artificial pressures in that market much bigger and more entrenched than you.
Essentially, the incumbents have been lied to for years and, now that new logistical realities are changing the status quo, it is very hard for them to understand why this is happening. They think someone must be cheating.
---
To expand on joosters' analogy of taking a fence down elsewhere in this thread [1], it's not necessarily bad if we take the fence down, we just need to realize that doing so may have serious consequences in the near-term. Having such a strong, deep-rooted artificial pressure in a market so abruptly removed may result in a painful readjustment of the market that hurts a lot of people.
(My other comments weren't meant as a defense of dealers, only intended to elucidate their operations.)