Yes, it does mean that.
If your goal is to demonstrate who is the best at recording points per unit of ice time, it is absolutely important to know what situations they played in. If you separate it into two situations, fine, but don't try to have a "catch all" stat that pretends that ES and PP time are the same thing.
(offensive GVT, for example, is a "catch all" stat that determines how many points a player "should" have, based on how much ES and PP icetime they received, not just a total number)
player A: 800 ES minutes, 300 PP minutes, 40 ESP, 30 PPP
player B: 800 ES minutes, 0 PP minutes, 50 ESP
who is the better producer? Player A has 3.81 points per 60 minutes, and player B has 3.75. Player A appears better, or, if we're not splitting hairs, they are about equal. And certainly, from a "hockey card stats" perspective, player A looks much better.
But if the only thing making player A the better "per minute" producer is his PP opportunities, what good are these 3.81 and 3.75 numbers? Why would we not want to get to the bottom of who was outperforming who? Those two numbers might shed light on who was better, or they might just shed light on who was playing on the PP and who wasn't.
Most players score at about double the rate on the PP. Player A did. Player B would also likely see a rate of production on the PP that was close to double his ES scoring rate. But because that wasn't how his coach used him, did that make him a lesser offensive player?
This isn't an absurd extreme example, either. This happens.
1. There are no catch all stats. The ones available leave out a lot of stats and context.
2. I have never pretended that ES & PP are the same thing. In fact I know they are not and that is why I said they would be weighted differently. If I have to use one number to compare players it is ES Pts/60 right now, but I don't do it without looking at the context. QOC, QOT, Zone starts, Corsi, etc.
If you weight ES & PP to reflect that only about 9% of ice time is on the Powerplay than you can come up with 1 number that is pretty accurate. Production is better than PPG and PPG is better than Pts. Production doesn't take into account the situational ice time differences though.
Seguin had a better Pts/60 at both ES and PP than Kessel but Kessel had better overall production because he played more on the powerplay where the rate is higher than ES. My number will accurately reflect this type of discrepancy and show that Seguin was the better producer based on rates instead of who got more PP opportunity. I think my method provides a very accurate list of the best players. It isn't perfect, it isn't catch all and it isn't predictive but it works for what it does and is better than Pts, PPG, or Production.
Your example is absurd and is certainly extreme. Only 9 forwards played more than 300 minutes on the PP and only 8 with any regular time had better than 6 Pts/60 on the powerplay. Giroux is the only one common to both lists. Only Crosby and Malkin had the overall per minute stats that you posted. If you had a player who put up these numbers as only Crosby and Malkin do than they are going to play on the powerplay.
You have basically compared an Eberle at ES to a John Scott on the powerplay who somehow has Malkin like abilities at ES. Your scenario does not happen. There are no players that good at ES or even half that good who get no powerplay time. If that happened there would be a reason for it such as Player B probably put up those points against weak competition so he won't see time on the powerplay and how good he is should be adjusted accordingly. There are defensive players who see little powerplay time such as a Chris Kelly but he doesn't put up a 3.75 ES Pts/60
My formula is a little more complex than just ES & PP Pts/60, but for simplicity using just those parts from your absurd example it still shows player B to be better but not by as much as just even strength shows.
Powerplay should be included and can be accurately included. It won't be perfect, nothing is. Pts aren't, Corsi, QOC, GVT, Point Shares. None are perfect or are really catch all numbers.
And back to the QOC/QOT measure. I feel using some type of production based measurement will be more accurate than shots or +/- based and it is not irrelevant.
If I can ever get the data I need in a usable form and the time than I will make my work available and I would put it up against anything out there now as a better measure of production/overall play and in turn using it for QOC and QOT that is more accurate and makes more sense to compare players across the league.