I'm basing it on a notoriously bad foundation. Let's get that straight from the start.
It's from talking with gamer friends, reading game forums and articles about games on the net. It's a cumulated impression from many years so no I haven't got any links.
Regarding my thought about why I believe going from TB to a landgrabbing and resource denying RTS is hard I can mention Endless Space.
It's a TB, or rather simultaneous move 4X space game. The forum on steam for it constantly have people posting that it's hard which it really isn't if you get one thing right. Expand at the beginning. Expand like a mothafucking crazyman berserk. Forget everything else just expand. Get land to deny it from your enemy.
This is something ordinary TB strategy gamers doesn't do. They build->expand->build->expand->build and so on. The only TB strategy and tactical subgenre I know of that do fast land grabbbing is those that play wargames. So hence I believe RTS that hinge on moving fast is a hard concept to grasp for someone new to RTS. I'll add that many of the threads on the Endless Space forum started with "Hi I've played multiple Civs, other TB 4X games and other strategy games without problems but this game kicks my arse!".
To be honest it was months since I looked at that forum so things might have changed.
The OP said he have experience with strategy games. RISK and Europa Universalis are strategy games. Not many rules about suppression in them. Don't mix strategy, tactical and wargames please. :)
Hm. Seems he only said TBS. Would be helpful if he came back and said what kind of gaming experience he have.
Now about DoW.
"Oh I can make a new troop type! I'll spam it because it had to have a new building or upgrade so it must be better and YEAH now I can upgrade it so now it's time to spam it at the enemy!"
That's a degrading way to look at RTS gamers but oh boy. I've met lots of them and I tell you they're hell to play with. Though you have a good point in that TB gamers probably would do as you say and actually look at what the description of the troop say so I give you that. :P
I did say it was a lite wargame. The concepts are not hard but I think you look at this from your own viewpoint a little too much. You have played a lot of games in different genres for many years I gather but we don't know if the OP have or if he have much experience with the concept of say suppression.
I'm playing it safe in my arguments which is that I start with that the OP is new to this sort of things instead of guessing what his gaming experience is. Again it would be helpful if the OP clarified this. :)
Ha ha I know how you feel in that last paragraph. Been there done that and often it have proven helpful to myself. :)