I'd like to make a clear distinction in terms.
"irrelevant" (meaning, nothing to do with it) isn't true, all those dimensions affect geometry, lift, wear etc. - the question is in what way, and how much?

"doesn't matter" is actually true in many cases, you get an error but the effect is very small, or 2 errors almost cancel each other out. Sometimes an accidental change corrects an unseen error.

"Push rod length doesnt effect geometry": well, not directly (a fixed length hydraulic pushrod is always "right"), but will if you need more adjuster to make it up.

"how much adjuster is hanging out doesnt affect geometry": it not only changes the ratio (more threads = lower ratio), it changes the angle between the 2 rocker levers (pushrod side and valve side), which is part of the basic rocker design. The rocker's inter-lever angle is the total of the pushrod angle (not the tappet bank angle) and the valve stem angle (15°, 18°, etc.). If the pushrod is 0° (parallel to the cylinder) the angle is just the stem axis. If the lever total changes (as with too many threads), the arc of either the pushrod side, the valve side, or both cannot be centered, and the sweep and scrub increase.

Yes, it's a complicated subject.