I'm going to disagree here.
Alice is a new user who has never used Word before. Between word 2003 and 2020, I grant she'll pick up 2020 much more quickly - point in favour of the new one.
Bob is an employee who uses Word just short of 4 hours a day, 5 days a week writing and editing reports (the rest of the time he spends in Outlook, excel etc.). If there's a task that Bob does 50 times in a typical week, then it doesn't matter so much to him whether it takes a bit longer to learn the command (after about the 150th time he'll have got used to it), but it matters a lot how fast he can do it once he's learnt it. Bob literally becomes more productive by having an interface which he can operate by muscle memory, in a way that more than pays off the initial training costs.
Think of keyboard shortcuts for example: they're completely unintuitive to a newcomer, but with experience, Control+Z and Control+C, Control+V and the like save time, and time is money. My favourite word trick in this category, incidentally, is Control+Space "remove formatting" for text you've pasted in from elsewhere; it doesn't work all of the time though. You used to be able to do Control+Shift+V for "paste as plain text", I don't know which version removed that again but I consider it a great loss. Paste -> Keep Text Only takes just longer enough to be annoying.