A few things:
1) Fair point about JT, maybe it came from above -- if it did, Dubas did a good job bringing the value down to 11m. If I remember right, JT left a few million on the table, pretty sure he had another higher offer (SJ maybe?), but JT was a UFA still at the back edge of his prime, those guys always get overpaid. We don't know that ownership was behind that signing (I doubt that's the case, but it's possible), but if so Dubas did well getting JT at a lower AAV than what he would've gotten elsewhere.
But I don't think ownership was behind the signing, my guess is that if it was an ownership call that Leafs would've made JT the best financial offer, which they didn't do. Neither of us really knows.
***
2) I don't think most people are realistically saying Leafs should've gotten AM34 and Mitch to sign for single digits AAVs (well, to be fair it looks like some ppl are arguing that, sorry about that). Personally I think the bigger issue is the term. With a cap that increases, the term matters much more than the salary, you'd expect an RFA (yes, an RFA) to only be able to negotiate one or the other. Here, both Auston and Mitch were able to negotiate both. While they were RFAs.
This has not happened in any other team in the entire league. The Leafs owned both these guys' rights, why did they give in to everything. I place that blame 100% on Dubas and no one else.
***
3) To your point about Lou, Lou is not only cheap, he generally builds his team from the net out. Look at what he did in Jersey and what he's doing now with NYI. He also does not care at all. Meaning if mgmt told Lou to sign Tavares, Lou probably would've told then to go to hell and then used the cap to sign guys like Spencer Knight, Chris Tanev, Adam Pelech. Probably not those exact players but you get the idea. If Lou were in charge of the team, there's no way he would've prioritized signing JT over a proper 1D and / or starting goalie. Those pajama boy memes never would've happened. He's also a good negotiator and he would've got AM34 and MM either at the full 8 year term, at a lower cap hit, or both. See how Yzerman got exactly what he wanted with Debrincat, Lou's a better negotiator than Stevie Y.
***
Either way Leafs as a team are not built correctly, no 1D, no long term goalie, no cap space. I'm a neutral (Zona), but completely understand why Leafs fans would be upset at Matthews (or any of the core) demanding to be the highest paid core in the league. The roster has too many holes for an actual cup contender, from the outside this whole thing just seems weird