In their late 20's, those deals made sense for Ekblad and Bennett, but Marchand has recently turned 37, so when he signed a deal that took him until he would be 43 years of age, it certainly raised some eyebrows around the NHL.
This all occurs around the time the NHL have stated they are looking to crack down on cap circumvention, with Alter later stating that for all intents and purposes, that's exactly what this situation is.
At the end of the day, it's highly unlikely the NHL will look into this, but in the history of the league, very few forwards have played until they are 43-years of age, and with Marchand unlikely to buck that trend, analysts and insiders are starting to call out the deal for exactly what it is.