> I don't see what's lost by deleting it until someone's willing to put in the effort to write something substantial
He's mentioned as creator of Gravatar and co-creator of Github in their respective Wikipedia articles. When someone is mentioned as a prominent figure in connection with something that is Wikipedia-worthy, it is quite natural for someone reading that article to wonder "what else has this guy done?" and want to click his name to find out. Now people who ask that question have to resort to the search box.
Deleting articles like this also, I suspect, reduces the chances that someone will put in the effort to make a more substantial article. Someone thinking of doing so will see that there once was an article and it was deleted, which will discourage them as they might worry that their work too will be deleted. Better, I think, to leave it there as a seed from which a more substantial article might grow.
Wikipedia articles aren't intended to express a graph the way a "who's who" database does. Every article in the encyclopedia is expected to do a good job summarizing it subject and providing a guide to reputable sources on that subject.
The problem with stub articles about people that serve only to map a person to every Wikipedia subject they've touched is WP:BLP.
To sum that up: every article about a living person has to meet a higher standard of "not being wrong about that person", because when Wikipedia lists something wrong about (say) Tom Preston-Werner, it's plastering that wrongness at the top of every Google SERP, and this tends to piss people off. For obvious reasons, BLP articles are also a magnet for the most insidious kind of vandalism WP deals with: negative claims about real people that are difficult or impossible to refute "automatically", which is how virtually all vandalism on WP is handled. WP BLP articles thus incur a liability for the project.
Often, that liability is more than offset by the value of the article itself. But here, it seems like much of the value of a T.P-W article is simply in making it slightly easier to search for T.P-W in WP. But WP already does a pretty good job of doing that. Marginal value, maximum liability.