You aren't the only one seeming to post as if roll20 or foundry is the
only VTT out there but people have been telling you for a while that the things you are saying that wotc's barely described VTT might solve have long been solved by other VTTs they use. In actual play doing that is a lot less "fiddly" than it looks when trying to cram a specific example into a short as possible video without dragging it out with any of the
many many features that are extraneous to the example. I had originally done a video that made the little room with the barrel too but it was more than twice as long & most of that time was pointlessly picking desirable assets for it
In actual play at the table
the biggest hurdle is not in what I'll paraphrase from 287 as "quickly scrawl some stuff on a whiteboard", that hurdle comes in needing to draw hundreds of feet of stuff in one or more directions because 5e is too PC friendly in expanding the area of scrawl a player can feel
justified in expecting to see filled in within the rules. Having 3d makes that an even bigger hurdle by increasing the load on the computer & possibly the GM.