You are correct, the team isn't going to miss the playoffs or play .500 hockey down the stretch. They are a good team. Capable of beating other good teams.
The problem is that there's a flip side to that coin. They are a good team, not a great team, like probably 8 other good teams out there.
When everyone is buying the same assets at the deadline there's a tendency for both the team and the fanbase to get on blinders cause everyone is rushing in the same direction, but really, if everyone rents, then you haven't moved your own needle.
To get ahead - in business, in life, in sports - when everyone else zigs, you have to zag.
That doesn't mean the team has to tear down to it's studs just because its a middle of the road playoff team, but, yeah, they "aren't great," at 5v5, which is another way of saying they kind of suck at it. It's a fatal flaw that probably gets them in the end.
Consider that when deciding what to trade away. Bolstering themselves long term is going to be the better value proposition and it's what they should do. It doesn't mean punting on this season - if lightning strikes, and the hockey gods want Shesterkin to play like Hasek and Panarin to play like a Conn Smythe winner and Lafreniere goes on a tear, this team can win (hell, fate chose the Blues to win in 2019). But it can do that with or without trading a first for Sean Monahan.