I assume by they - you mean DM and the coaching staff - and as he's been on the bench and used in recent games they presumeably haven't written him off so that would make me right - not wrong.
It's a matter of opinion there is very rarely any topic on here where you can be right or wrong which is what makes some of the statements people make so amusing.
Maybe Saha does have "a lot more to offer from the start" but what he consistently is not offering is goals - and that is a fact I know I'm right on. Most supporters now feel they have definitely seen enough of Saha to reach an informed opinion that he's not who they want to see start and would therefore like someone else to be given a short run to see if they can do any better - which may of course not work and you might end up being proven right after all!
How does it make you right?
He's good enough to come on for the last 10 minutes and try to bully tired defenders. He's not good enough to start games. It's not rocket science.
Which brings me neatly to my next subject, when you say: "most supporters now feel they have definitely seen enough of Saha to reach an informed opinion that he's not who they want to see". Now, that may well be the case, I don't doubt you, unfortunately most supporters can't tell their arse from their elbow when it comes to football. This may sound harsh, but it's true.
Trying out a player who's obviously not good enough in training just to see what happens, well, it's as stupid as it gets. If Moyes tried to do it, I'd be furious. Saha is in an unbelievably poor form and is low on confidence, but as I said, he still gives us more than Straq or Vellios in open play, and still gets chances. Once he starts converting those chances, people will be raving about how he's world class and maybe even praise his movement and link-up play, which is the best we currently have. (Still not as good as the Yak was in his prime but that's life.)