I suppose you could argue many things? I would not naively expect Perl's versioning behavior, and a system package manager will have many users who are not Perl devs but who may nevertheless have Perl packages installed on their machines. "There is more than one way to do it" is fine for some things, but I also think it's desirable behavior for a system package manager to only require users to learn a single versioning scheme. In gentoo's case (and in most cases of system package managers I've seen), this happens to be dot-separated sequence of numbers, not floating point.

A system package manager also needs to be able to compare versions, and within gentoo's dot-separated versioning scheme 1.2 < 1.12. However, a perl package could have a dev sequence of 1.1, 1.12, 1.2. If these versions are entered naively into the gentoo packaging scheme, the intended order will not be preserved. So there must be some conversion in order to handle it correctly.