I think largely because they are estimates; I think Craigslist is likely worth way more given the ubiquitous nature, high margin, low costs and the decisions to not monetize everything.

That said, IMO this article is not about Craigslist but a subtle advert for the 2 "competing firms" that are mentioned. I have seen an uptick in articles about Craigslist mentioning them and had never heard of them before.

Potentially cynacism on my part.