It's one click to switch to splitscreen ...
and then? if you want to customize your layout some more (more splits, change area sizes,...)? that's cumbersome with an application which isn't designed for it.
Now they have. Been a while that i have used a splitscreen layout last time ...
max, maya, blender,... had this since their first versions in the nineties.
But doesn't the fact that so much people are in trouble with the current Blender UI tell you that there must something wrong with it?
not really. sure there are problems with blender's gui but not really more than in most other applications. in the 3d-animation classes at my university people new to 3d were in a lot of trouble with houdini and maya too.
i guess blender also is much easier to give up on since no money investment is involved with it.
