Hardly a good reference, Internet Archive is older than Wikipedia.

Wikipedia itself is only a little over two decades old. I don't think anyone would parse "many decades" as "two decades".

There's also OpenStreetMap, exactly two decades old and thus four years younger than Wikipedia.

> Wikipedia itself is only a little over two decades old

The world wide web (but not the internet) is only 3 decades old!

Let's Encrypt is very good but it's not exactly a web app, semantic-web or otherwise.

Not true: Wikidata, Open Alex, Europeana, ... and many smaller projects making use of all that data, such as my project Conzept (https://conze.pt)