No I think its just cheaper, if it was stronger you normally would have a metal plate or the entire base would be metal. The only time I have seen those fail was actually the hinges themselves and not the attachment points. If the metal plate or base somehow got severely damaged I doubt it would cost much more to repair and its still unlikely to damage anything else.
I currently do this with mailbox .org, I spend 4 euros a month for 2 accounts (3+1). This allows us to use the same domain, share storage and sync calendars. Mailbox also stacks up pretty well against proton in security and privacy just doesn’t have a free plan and some of the little extras. It also supports catchall and full filtering if you really wanted to save the extra euro and use one account.