Lots of people getting hung up on specific details... but the actual practical benefit of 5G over 4G is simple:
5G can have an order of magnitude more devices connected at once. This will allow us to have more things connected to the network.
4G ran up against the limit to how many devices per square mile can be connected a long time ago in densely populated areas. The transition to 5G has solved the issue. It's even solved it for 4G users, since there are now less 4G users.