I hope I am not being unfair, but a key weakness, relative to Moodle/STACK, particularly for students at more basic maths levels, where simplification is still being learned and tested, is a more straight-forward method of controlling the degree and type of simplification allowed, e.g. so that simply typing in an expression given as part of the question doesn't get you full marks, with Moebius/Maple doing all the work. I know there are ways of doing this via convert() and InertForm:-Parse() functions, but I have to repeatedly remind myself of precise syntax, or use template code, each time I try. This method is opaque to less experienced colleagues. Yet this basic issue comes up all the time with starter-level questions. There is a lot of documentation on this, and a fair amount of online Maple/Moebius forum help too. Attesting to the issue being tricky.
( I haven't had time to tinker properly with MathApp/Maple Workbook style question type yet, which, may I vaguely recall may help on the defined/controlled simplification front).