Let me put my objections this way-
I think that hindering one enemy is a roughly, minimally controll-ish type of thing to do. However, if the entirety of a character class's ability to engage in controller behavior consists of various ways to hinder one enemy who happens to be within melee reach, I think that class is NOT a controller. It may dabble lightly in controlling, but it had better not be a controller full time or its going to be hopelessly outclassed by any other class who can hinder multiple enemies at range.
Think about it. In this corner, competing for the title of Competent Controller of the Year, we have a martial artist who can trip, and maybe throw, like, one dude. In this other corner we have a wizard who can open chasms in the ground to impede enemy movement, debuff multiple foes at once, force enemies to scatter with the threat of area of effect evocations, and grant his allies the ability to see in the dark, fly, or otherwise bypass environmental hazards which afflict (or which he has inflicted upon) their foes.
See my objection?
Imagine that your party is being attacked by a wave or orcs, with spellcasters backing them up.
If you respond by stepping to the front lines and stopping the charge as if it were a wave crashing against rocks, you are behaving as a defender.
If you respond by slipping through, around, over, or firing past the wave of orcs in order to stab and/or shoot the wizard in the face, you are acting like a striker.
If you respond by exploding the wave of orcs in order to teach them a lesson about bunching up, or by walling off part of the battlefield with a cloud of lethal miasma so that the orcs cannot charge the party all at once, you are behaving as a controller.
If you decide which of the three things listed above are most important to the party's victory, and you selectively aid that thing in getting accomplished, you are behaving as a leader.
Most of the so-called martial controller abilities listed above actually help the most with stepping into the breach and stopping the charging line of orcs from reaching the party. The fact that you might do so by tripping them instead of by hitting them with attacks of opportunity isn't really relevant. Its not the power source you use, or the technique you use. Its what you're accomplishing with it. If you're defending, you are a defender, even if you do so by knocking people down and dodging their attack, instead of absorbing it with your armor.