Even if you are not a technical user, you should respect the fact that proprietary formats will bite you. Look how many this guy alone used. If you use opensource, even, the mbox and mh all email, one giant file paradigm is all nice until it is corrupted.
I wish more clients respected Maildir underneath, or tried to bend the truth on Windows FAT32 and NTFS ad the ; in path names limitation is a pain.
https://en.wikipedia.org/wiki/Maildir#Filesystem_Compatibili...
Sadly even Thunderbird has struggled to re-engineer a Maildir subsystem where it was never intended. Show me any email client devs who had the khutzpah to even dare that.
https://bugzilla.mozilla.org/show_bug.cgi?id=845952
But you have a lot of safety in spreading it across files, and you can throw dumber full text search at it, shell scripts, and a lot more flexibility over all.
Sadly, some Unixisms will never escape Unix culture. As someone who has watched people screw 10+ years of email in Thunderbird n>1 times, I wish for the love of God everyone would use Maildir in the client, regardless of interface, free or not, et cetera.