Fanatics has Skyridge 9s & 10s every week in auction, plus many other high grade wotc holos. There is just as much, if not more than Alt for English vintage. I have followed both platforms’ auctions weekly for the past couple of years and while I haven’t done any hard counts, I feel confident in saying it is only more recently that Alt has started to catch up on the EN vintage front (with most of those cards coming from the same pool of sellers).
Fanatics does tend to get more high-end JP prize and trophy cards than Alt. Last week there were multiple Illusion’s Zoroark/Zorua cards, Fan Club Eevee, Grand Party and Masakis. If those aren’t what you’re after, that’s fine, but there’s no need to downplay what gets listed on Fanatics just to make Alt seem better (vote in my poll if you want to do that).