Are they? A traditional RTS like Age of Empires 2 or a Starcraft requires quite a lot of accuracy in quick-selection and movement orders, it would drive me nuts to try and do that on a mobile screen with no mouse. I know MOBA-style games are popular on mobile, but there's only one unit to control there.

The only non-keyboard-and-mouse RTS I can think of is Tooth and Tail[0], designed to play nicely with controllers (in a similar way that that Halo Wars was back in 2009), and while I'm sure high-level play in those games was indeed very high-level, the whole experience nonetheless just doesn't work for me, it feels 'dumbed down' still.

[0] - https://store.steampowered.com/app/286000/Tooth_and_Tail/

I do not think that is the case for traditional RTS games. At first glance, sure you touch the unit you want and you touch where you want them to go. But there is a reason why single button mouse to two button mouse was a huge improvement for RTS. You don't always want to do one thing or have it be context aware. The other is that RTS games typically involve you dealing with hundreds of units, all across a map, so things like hot keys to build additional units, or control groups to manage different unit groups is critical. Mobile seems like it could work for some casual RTS games, with small numbers of units. But not for a traditional RTS.

One might assume that and it is mostly true for round based games, but for real-time you just cannot achieve the actions per minute needed on touch. A game like Starcraft or similar is barely playable

I could see a casual RTS working, one where you select groups of soldiers rather than individual units.

The best game I've ever played on mobile is Eufloria, which is an RTS. I wish there were more games like it.