Ifithadntbeenfor etc. Emre Can has had injuries too.
As for the last paragraph, you don't know that Klopp agrees with that. I do know that he has started him in 75-80% of his league matches in charge. I also know that he has chosen Can ahead of Wijnaldum in plenty of games when those four you mention have all been fit. The 6-1 against Watford and 4-2 against Palace are two examples last season. Spartak away & Burnley at home more recently. I also know that he's chosen Can ahead of Henderson in plenty of games. Burnley at home, Maribor home & away recently. Albeit with Henderson I do think it's often with the dual purpose of giving Henderson a rest and Can a partial rest, i.e. not having to undertake as many intensive sprints playing in that deeper role.
Never denied that Can has started individual games ahead of one of the others. We will see more of it this season, with us having regular midweek fixtures.
But if you look deeper, those were the exceptions rather than the norm, weren't they? Who was the least used midfielder out of the four in the first half of last season when all were fit? It was Can. Who were the regulars? Henderson, Lallana and Wijnaldum. Let's not revision that period. We can count appearances and minutes until Lallana got injured. Last season, when we were blowing teams away and playing fluent football in the middle, this set of Hendo, Lallana and Wijnaldum were getting high praises and rightly so. I don't remember Can being exclusively noted for that part, where we were looking like genuine title contenders. In individual games, yes he has featured and done well here and there, but he won't be remembered as a big part of that midfield at all.
Minutes clocked in the league by our midfielders last season overall (I'm giving the entire season, including when he started to play regularly later in the season to give Can a better chance)
Can - 2368 mins (missed a month due to injury)
Wijnaldum - 2978 mins
Henderson - 2118 mins (missed 3 months due to injury)
Lallana - 2113 mins (missed approx 3 months due to injury in three different spells)
You would think his minutes tally would be closer to Wijnaldum's than the other two if he was that much of a first choice, as both Henderson and Lallana missed a third of last season due to injury, however that's not the case.
If we only consider the minutes played by Can until the end of Dec (Lallana and Can missed a month due to injury each within this period),
Can - 778 mins
Wijnaldum - 1378 mins
Henderson - 1668 mins
Lallana - 1205 mins
This is a reality check for those who think he has been first choice under Klopp at any of the No. 6 or No. 8 midfield positions. Especially, not at No. 6 ahead of Henderson. The difference in minutes played when all are available is alarming.
On the contrary, Can was a big fixture in the second half of last season. Underlying context - no Lallana for some more time, not Henderson for a long time. As fourth choice for a three man midfield, he was definitely going to play if any of those got injured.