Chiarot's is because he (like most veteran physical shutdown D) are overrated among teams and undervalued on these boards. I think Toffoli was generally viewed as being worth a first +, the quibbles were about if teams were able to take him without retention (Montreal ended up taking Pitlick's contract back to make it work for Calgary).
Lehkonen was the strange one, but from what I remember it depended on the fanbase. I recall Avs (and Rangers fans, but he wasn't traded there) being particularly ignorant of both him as a player and what Sakic would do, but other fanbases were more reasonable.
It feels like part of the Monahan thing is the fanbases involved. Flames fans are (rightfully) salty that they spent years hoping Monahan would bounce back, saw him moved with a 1st and now see that he could get a 1st as a rental. Jets fans are probably pretty tired about all the Dubois discourse and are feeding it back to the more unreasonable Habs fans. It depends on the Avs fans, but a lot of the ones that didn't know anything about Lehkonen are also ignorant of what Monahan has done in Montreal.