I would agree in general with what you said in that I think we all fall into the trap of thinking the PE discipline exam we took is comparable to all the other PE exam's which is likely far from the truth. I know I do/have.
To his point the way the Civil AM exam is structured, it discourages experience. At a minimum 80% of the Civil AM exam is purposefully over material a test taker almost assuredly hasn't seen since college... which is dumb. The intent of the Civil PE exam (AM portion specifically) is to test you over material you have no experience in and don't see on a day to day basis, no likely will ever deal with in practice. Civil PE's usually specialize in WRE/Structural/GEO/Transportation/other... not all of the above. Therefore, in that specific case, experience is "bad" as the more experience you have (in terms of years of practice) the further removed someone is from having learned or dealt with the material that is on the AM exam. The PM exam is somewhat the opposite as it should be over material that tests a combination of your experience and college tutelage. For this reason, experience is at best totally irrelevant to the Civil PE exam, and arguably counter productive at worst. BUT that is likely not true for many of the other disciplines. I would assume (hope) that the other exams do a better job of actually testing one's ability to do their job, which in part is based on ones experience.