Punch in out is a basic feature of any kind of recording stuf, looper is one…
Overdub is a completely other thing, but if you already have
it, its easy to implement punch in out = rec on rec off…
Punch is “replacing”…
May be you are always happy about your loop? always in tempo? always start at the beginning?
may be you don’t want always redo your loooong 32 bars loop because you miss one fu… chord or something else???
In live (or not) i always prefer punch in out, because it will continue to record until I m satisfied… i don t need overdub with 6 stereo tracks…
And I always re record the beginning of my loops to avoid the reverb, dly, sustain cuts…
Try other loopers, DAW, etc… , you will understand how punch I/O is usefull…