Wrong. What a coach should always look for is the right fit for each line. You could put two solid wingers with Schenn at center and it would still be klunky.
Weise worked with Couts last year, if you put them together in TC and it clicks, you don't go "gee, Weise isn't one of my nine theoretically best forwards." You go, ok, these two seem to fit together well, who do I want to put with them and see if they work together as a trio.
If Flippula isn't comfortable at LW, you don't force him to play there just to get Patrick 1 minute a game at center for the first half of the season (you do look to trade Flippula near the trade deadline, however).
This is why they have training camp, to see how new players mesh with returning veterans and try to find the best combinations, both forward lines and defensive pairs. You're talking real players - not video game players - and real people perform better when they're comfortable. So a coach has to try and find the right combinations (and break them up when a line or the team gets into a rut).
Now odds are the better players will work together, IF they have complementary skills, but sometimes lesser talents are a better fit because they may not have the whole skill package, but they have a couple skills that make their linemates better.
Plus, you have to account for road games, where opposing coaches can counter your best lines, do you want different lines on the road that will present harder matchups?
The good thing is the Flyers have the kind of talent where Hakstol can try some different combinations, big lines, speed lines, skill lines and a checking line that can actually play.
PS: During actual games, your lines inevitably get muddled, if Couts and Simmonds are coming off a 4 minute PK where they played the bulk of the minutes, you'll want them to skip a shift, if you've been on the PP, the second PP unit has to be able to revert to ES play, and so on.