[quote=@The Nexerus]Language's constant state of flux is not a reason to defy the structural rules governing language, but rather to reinforce them in order to sustain intelligibility in spite of the change.[/quote]

But that line between what you view as intelligibility and actual evolution in dialect and slang in pockets of culture is basically impossible to define, attempting to organize any set of rules for language based on intelligibility and avoiding ambiguity should be exactly that. Governing beyond understanding on a casual level is simply emulating some archaic linguistic history for the sake of those setting the rules. In the context it's fairly easy to understand what "..Post if Your Depressed" means. It isn't laziness, it's people realizing conflating the two words is convenient and the next step of evolution for the word-- you can understand what is being said based on the context of the sentence.