For what it's worth (anecdote incoming) I use a touchbar MBP with a Dell UP2414Q, which is driven using multi-stream transport. Effectively its panel is presented to the system as two separate displayport streams running daisy-chained over a single port. Once I found the right cable, everything worked fine. (The first cable was advertised with DP1.2 and MST support, but it would only operate in the legacy mode that dropped down to 30 Hz).
God forbid you try to use this with Windows though. Sometimes half of the screen cuts out, sometimes one side of it shifts by a couple hundred pixels (and wraps the right edge of the image around to a stripe down the middle of the screen), and god knows what other problems that I can't even remember. This was with a GTX 900 series GPU which is definitely "supported."
I used to have it hooked up to my Windows desktop since that's the fast computer with more storage and RAM, so it should be great for stuff like Lightroom. But since the screen doesn't work reliably, I moved that back to my MBP.
A friend with the same screen had identical issues on Windows and a similar solution. It's now on his wife's desk for her to plug her Macbook into.
Display signaling has gotten a lot more complicated than DVI/VGA were, and the reliability problems that have cropped up from that are present across the industry.
