Most of the justifications that your anonymous advisor lists are either half-truths or outright false.

AS can be very good or not good at all, depending on your needs. It makes the most sense for people who fly or can fly AS, and also for people who split time between AA and DL and are OK with positioning on a paid ticket for international award redemptions, or want to redeem domestically only.

I will also say if this person has been "trying to use 80k miles with DL for years" they are not necessarily very familiar with DL's program and product. He does not even know the mileage bonus for Golds!

Access to exit row if not taken is OK, I guess, but not nearly as nice as EC or upgrades to F.

If you're an elite on DL you will get much better phone agents than your advisor.

I don't think DL's food is necessarily worse than the alternatives. The bulk of it I would not characterize as "unhealthy". I wonder how much or how recently this person was even on Delta F?

AS is partnered with a limited set of oneworld and skyteam. Their partnerships are nice, but not nearly as broad as your advisor claims. You can also only mix AS + 1 partner on an award, so if you do not live in a city served by AS or the partner you wish to fly, you must get a separate ticket to position yourself to a city the partner serves when redeeming awards.

In other words, if you're not in an AS city or a city served by the airline you want to redeem on, you are either restricted to DL and AA for international redemption, or you need to buy a separate ticket to get to your award.

The "systemwide" upgrades for AS are usable only on AS, so you need to be flying them or violate the program rules and risk losing your account for those to have value.

AS is a good program and can be a reasonable choice, but your advisor does not know what he's talking about so I would not trust his advice.