Bottom view, with pins labeled in a clockwise direction, was the standard for vacuum-tube base diagrams, since tube sockets were always wired from the bottom.
Old conventions can live on.
Exactly, & it made perfect sense, as analog clocks all were numbered that way.
If you were probing tube sockets from the top, you just (easily) kept in mind that the rotation was a mirror image of the normal diagram.
With the first DIL ICs, as people trying to troubleshoot them were as likely to be probing the pins from the top or bottom of the PCB, it again made sense to maintain the clockwise diagram, as those brought up on tubes would automatically make the adjustment.
It was found, though, that much probing was done from the top, so it became more common to show the top view, with the numbers naturally rotating anticlockwise.
Discrete transistors were normally probed from the bottom, so it became natural to draw them, or anything else in a similar package from the bottom view.
If you want something confusing---back in the day, optocouplers were commonly packaged in a 6-pin package (DIP 8 with two missing pins).
As they were seemingly all pin for pin compatible, & many had very similar characteristics, it became relatively common to swap types with little chance of a problem.
Siemens, however, decided to go their own way with a totally different pinout to optos which were otherwise similar to "jellybean" ones.
A "trap for young (& old) players!