There's definitely a hit to search traffic if you go this route, as Google is unlikely to rank you above a competing article for a competitive keyword based on only an excerpt. The Information simply doesn't care.

They have an expensive subscription ($400/year) that I'd guess targets VCs and tech execs, which is a very specific segment that's best reached via means other than Google search, anyway.

But yes, to your point, successfully paywalling a media site in a way that's impossible to bypass is trivially easy to do. Most media sites just don't think it's worth it.