They're intentionally using straw man arguments to avoid the actual point and be dismissive.
Some posters have dug their heels in ideologically to the point that they will refuse to even acknowledge this being of any significance. We've slowly gotten to the point now where "of course we want physicality, assuming they can play!".
This team needs to get a metric f*ck ton harder to play against. On D, in the top 6, in the bottom six, you name it. When the "playoff" type games come around (Boston, Tampa, Winnipeg), it's convenient that we have guys like Benn, Simmonds, Hunt, etc. dressing and having to settle every score for the team. In the playoffs, you have guys like Lyubushkin being over utilized, way out of their depth, because Keefe is salivating for any semblance of physical compete. Yet, these players are trash and won't move the needle when it matters, so it's a mirage. When 3/4 of them are inevitably scratched, nobody steps up.
At this point, I am not even sure there is an actual point. The idea of toughness changes all of the time. Sometimes it is we need a guy who runs people through the boards, fights, etc. We have seen people throw around Ryan Reaves as a solution only a few months ago. People still want Simmonds playing in games when there is really no circumstance, short of a ton of injuries (and I mean a ton of injuries), where that should happen.
Otherwise it is needing guys who are "tough to play against", which seemingly has a lot of different meanings to different people. I think some guys who are being considered "soft" are very tough to play against, and I think we have had a lot of physical players who have been super easy to play against. A lot of guys would probably love to play against a guy like Simmonds or Reaves right now, as long as they don't have to fight them.
There were people constantly advocating for Lyubushkin to stay in the lineup, and claiming how good he was, even though he was a steaming pile of garbage who was carried by Rielly most of the time. Even in the useful physical stuff, like board battles and net-front coverage, he was often worse than the guys who everyone claims is "soft" on our back end. He just threw a few huge hits once in a while and that made some people think he was really good.
So the goal posts are definitely being shifted when it comes to toughness. And there have certainly been a ton of clamouring to make this team worse in favour of adding toughness to the lineup. Without a doubt.
My position on toughness has pretty much remained the same. It has to be useful, it can come in many forms, and it is often overrated (at least in its traditional form). Win board battles, put pressure on the other team on the forecheck, work hard in all three zones, go to the tough areas to score and work hard in our own end to make sure that the other team doesn't get easy chances. You don't need to be very big or traditionally physical or throw a ton of hits to do those things, and those win you hockey games. I like a lot of the energy guys the Leafs have brought in through the draft beyond just Knies. Tverberg is going to be a fan favourite in that regard, and it is why I like Joey Anderson a lot too. Both are around 6'0", 200 lbs and their high energy style compliments a solid set of skills (Tverberg even has some above-average offensive skills).
If you are big/physical/throw hits as well, then great, but it is not enough on its own. There needs to be a lot of foundational skill beneath it to make it truly worthwhile, and there just are not a lot of guys in the league who possess those skills enough to be worth having in a lineup over other guys who maybe do not throw as many hits or are as big and physical... And those who do are either extremely rare and valuable (Knies could be that), or are made out to be much better players than they actually are. Hence, they are overrated (Knies could also be that).