[nerdponx]

Stepping in and out is an extra step, mentally and physically. It's increased burden on my working memory, which is usually already quite full keeping track of other aspects of the task at hand.

Also it imposes more burden on the author, and possibly could lead to developing the wrong abstraction, which we all know is bad.

[tharkun__]

I don't get that. If you need to step over a function call you just remember 'oh right, step over doZ()' vs 'oh right this is 78 lines in which the code does Z, and dang I'm stepped 24 lines into it already before noticing. Where was the end of this again so I can skip ahead?'

One of those seems easier to me. Potentially our brains just work way differently but I have a much easier time remembering that function name I will step over.