Matt, I know you know there are rules that the PGA has for such and yes, I agree that they don't enforce them very well, do they? It is my theory (and only a theory of mine - not substantiated at all) that this has "gotten away from them" (the PGA) due to the increase of money involved in the tour over the last 30 years or so.
Scenario 30 years ago: Purses were less (even inflation-adjusted), TV contracts were less (even inflation-adjusted), rules were slightly easier, the PGA had tighter control over situations as - except for a few select players who were bigger than the game - players weren't 'celebrities' (or prima donnas) as much as they are now, the crowds were much smaller / easier to control, and the players themselves (of 30 years ago) were taught by crotchety old stern disciplinarians who would've strangled their pupil / student if the latter would even think of taking more than 4.5 hours to finish 18 holes in a 4-some.
Scenario today: All the reasons stated above where it takes longer to play.
And the reason is no one wants to "kill the cash (fatted) cow"! Not the players, not the PGA, not TV, etc. Until we / they hit a wall of intolerance (in the guise of lost viewing audience numbers) it will only get worse.
That is unless someone / some governing body has the insight / gumption to foresee it coming and do something about it.
We can hope.
Karl
Ps: Same goes for the PDGA