RTP is correct. A Goodyear-welted shoe can only take a finite number of re-weltings. It's a bit deceitful when people tout GY-welted shoes as being able to last a lifetime as long as you maintain the uppers and have them resoled. This is more true if you leave the welt in place and simply replace the sole. A welt can theoretically withstand several resolings before it has to be replaced (assuming your wear pattern doesn't chew into the toe as some do). However, in order to do this in an aesthetically attractive way, the new sole should be sewn to the welt using the same stitch holes, which isn't very easy with the rapid stitching machines that are employed these days. Otherwise, you will have lots of "empty" holes in your welt from where the machine didn't line them up with the old holes.
The problem is, most factory recraftings don't reuse the old welt for this very reason. Also, the welt can sometimes sustain damage when cutting the threads between the welt and the sole. To mitigate this, and to maintain an efficient streamlined factory process, the manufacturers automatically replace the welt, cork, sole, and heel without question. In this process, the uppers can only be re-welted ~4-6 times before they have been perforated with so many needle holes that they lose their integrity at the inseam. Eventually they become brittle like tearing a piece of paper at a dotted line.
So, yes, resoling a shoe with the manufacturer does have a detrimental impact on the long term longevity of the shoe simply because you are "burning" one of your finite number of recraftings that they can handle.
An exception to this is a high quality cobbler such as B Nelson, who will reuse your welt, assuming it is still in good shape. Also, when they do replace the welt, they will hand-stitch the new welt through the original holes in the uppers, thus saving wear on the leather at the inseam. Theoretically, sending your shoes to someone who gives your shoes a greater level of hand-care will make them last longer. The problem is, these companies don't have the original last, which can theoretically cause problems such as the shoes not maintaining their original shape and size. This isn't a frequent problem obviously, otherwise people would not use them. However, the potential for the problem exists. They will also "improvise" when necessary, using salvaged materials from other shoes, scrap components, etc. Some people enjoy knowing that their shoes contain original manufacturer's quality components, others don't really care as long as the shoe is functional. To each his own.
I ask cobblers a lot of questions about their process before I trust them with my shoes.
Thanks for clarifying MWS. Always nice to read your feedback!