Why does Rick Steves still refer to Amsterdam as a seedy place best visited as a day trip?

I was in Amsterdam for the first time last year, and it's certainly true that Amsterdam is not seedy. And it's also true that many travelers there like to stay in Haarlem. (There's also a regular poster on this forum who is from the Netherlands who frequently recommends staying in Haarlem.)

I'm not aware of Rick Steves referring to Amsterdam as seedy. Can you share a link to where he's said this, or where it appears in his guidebook?

Gee, I had no idea Rick was dissing Amsterdam. I would never consider staying anywhere else than inside the Singelgracht.
His "Heart of Belgium and Holland Tour" has a 3-night stay in the city, but the "Best of Europe" stays 2 nights in Haarlem and commutes to Amsterdam for a day.

I wouldn't call Amsterdam »seedy« or a »bad place«, unless one is sensitive to the idea of the Red Light District and the existence of coffee shops. Having said that, there are good reasons to consider staying in Haarlem - or other nearby cities - instead of Amsterdam itself. Amsterdam is getting crowded, very crowded with tourists. Hotels are expensive. And cities like Haarlem are interesting destinations in themselves and give the experience of a normal Dutch city.

Where does he say that? Is it in his book?

I'm looking at the website and I don't see such a reference.
https://www.ricksteves.com/europe/netherlands/amsterdam

I don't know why he would suggest staying outside of Amsterdam either. We fell in love with city, small and walkable.

From the into to Rick's Amsterdam book and the Explore Europe section of this site:

Best Home Bases:
▲▲▲ Amsterdam Progressive world capital with magnificent museums, wondrous waterways, Golden-Age architecture, diverse nightlife, and eye-opening Red Light District.
▲▲ Haarlem Cozy, quiet burg with its own top attractions, plus easy access to big-city Amsterdam.
▲▲ Delft Picturesque hometown of Vermeer and Delftware with college-town vibe — a good base for day-tripping to The Hague and Rotterdam.

Other parts of the text make it clear that he's suggesting Haarlem as very convenient for connections to the airport, the city (only 15-20 minutes by train), and other side trips. It's a worthwhile sightseeing destination in itself and also has several recommended hotel listings that are well under 100 euros for a double, about a third less than most listings in Amsterdam. There's no similar town that has caught his fancy near Barcelona, Berlin, or Rome.

That seedy Amsterdam: https://www.ricksteves.com/watch-read-listen/read/articles/europes-best-preserved-towns

I don't know we spent 3 night in Amsterdam Nieuwmarkt Square around the corner from red light district but you would never know it. Lovely area, lots of places to eat, pubs, people watch, walk to Dam Square, need a day for the Van Gough/Reich Museums, Anne Frank House, cannel boat tour, etc. We walked all over the city and felt safe and comfortable in our surroundings, one metro stop to Central Station and River Cruise stops. Love the place and will be returning in late May staying at an airbnb this time staying on one of the little islands near Central Station, Prinseneiland, can't wait to return.

My first trip to Amsterdam was in the Spring of 1976. I didn't find the city particularly "Seedy" that time, nor have I found it that way on the ensuing 15 to 20 trips I have made there over the past 40 years. I have always thought of Amsterdam as a world class city with wonderful museums, great art galleries, beautiful churches, and fine dining opportunities.