Stack-size is important. Of course I'm not often gonna play a medium, or low pair against the very tight/min buyin/all-iner who has just unexpectedly made an out-of-position move.

I almost exclusively play NL short-handed cash game holdem. Any pocket pair is a powerful hand.

You said initially that your calculations excluded bluffing. That's why the calculations don't work.

In practice your opponents will often bluff and if they don't show any strength (or even if they do), you should often bluff, or play back.

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If the point of the post is, that it not profitable to call medium/small pocket-pair's with the intention of setting, or folding; then I agree entirely.

However, pocket pairs should be profitable. Preflop raise, pressure the flop. Hit sets occasionally / fold from time-to-time.