Problem with the L298 datasheet
Those old bipolar processes could only be used to make crummy lateral PNP transistors with quite low gain so not very good for high current.
Using all NPN, especially those NPN, transistors is bad (because of the extra Vbe drop), but not as bad as it would be with monolithic PNPs.
Popular? Probably for legacy applications and hobbyists, but I doubt any serious application has designed them in within the last decade or more.