RHEL is going hard on XFS, they've even completely removed BTRFS support from their kernel - they don't have any in-house development competency in it after all. It's somewhat understandable in that regard, since otherwise they wouldn't necessarily be able to offer filesystem-level support to their paying customers.

Though it is a little bit amusing, seeing as Fedora - the RHEL upstream - uses BTRFS as their default filesystem.

Fedora’s gone the btrfs route, RHEL has all but given up on btrfs, pushing xfs

ext4 is literally just the latest version of the ext filesystem (AKA it has the most funcionality).

If you REALLY wanted MAX speed, you could make your system drive ext2, but you would lose some metadata, drive info & management tools.

It says it is "a" standard file system - not "the" standard. Very different things.