There's no true top players besides De Ligt and De jong.
Maybe Antony has the chance to be that 3rd top player (distance chance for Gravenberch, but think he will be buried behind the depth chart in Bayern).
But they are good at producing mid level players (not just Ajax, Holland in general produce mainly mid level players, not top players anymore as in the past) that make a good career for themselves in top leagues. But its not allways easy to shine outside the Ajax playstyle too for some of them.
Never even gave it a second thought! But yeah I have to agree. Made a quick glance on their bigger sales
https://www.transfermarkt.co.uk/ajax-amsterdam/rekordabgaenge/verein/610 and it seems you're all right. Wow! Blew my mind because, again, never even thought about it before.
Sneijder was two decades ago. Zlatan wasn't really developed there but is part of the same scouting era as Suarez among others (I assume). Given they have had more resources available in recent years they have also moved towards getting more finished products rather than developing their own. At least mixing it up a bit more with higher profile names too.
All that being said, I rate the recent prospects (MDL, De Jong, Graven etc) high. I would welcome either one of them with open arms. Although I have to admit I only know Graven from FM and youtube highlights.

The agents of the players, however, seem be more self-interested than player-interested. That De Jong wouldn't take Bosquets place was an easy guess. Timing was wrong. MDL's timing, wrong (not for us, but for him). Zyech to Chelski could only ever have been about money. I was a bit upset when van de Beek went to United because it was so clear that he didn't fit there and needed a system that suited his style. Had he taken another career path then I think he would be rated a lot higher, now he's "dead". Sanchez was too raw/young for the role he was to play in.
I've barely seen Antony so I'm quiet there, and I regularly confused him with Neres. Martinez looked error prone but promising whenever I saw him in the past but that was when he was young. I could go on but to me it seems modern agents have also had large impact on the career paths of young players. It's not just dutch players, same could be said about other leagues and clubs too. Overestimating the player and thereby giving poor advice or never really caring about other than €€€€.