@freelance—
Stan Kelly-Bootle once explained “It takes two to intuit.” A
lexical ordering (such as that provided by Excel) is only one of various orderings that have been or might be used. You can find systems in which “aa” immediately follows “z”.
Reader confusion about the collation is not much of an issue, because the site imposes a collation order; in reading, I know that “14.13” follows “14.2” because the presentation
makes it follow. And third-party software that were written without learning the collation order would almost surely have a variety of
other bugs.
Uploader confusion is a more significant potential problem; I'm not aware of uploaders expressing confusion under the present system, but they would if the proposal of the OP were adopted.
Replacing the used of labels such a “4.1” is not under consideration. The OP did not propose it, and such a proposal would be rejected by groups that prefer the present system. What is under consideration is
also allowing labels such as “14b”. And that then introduces the new question of whether a chapter labelled “14b” comes before or after one labelled “14.1”; because some uploaders will designate their chapters one way and others will designate theirs the other way. Some uploaders would use “14.1” for the first
part of chapter 14, and “14a” for the first
supplement to chapter 14; others would do just the reverse.