My experience with placement services is that none of these people seem to work with remote candidates, and many have a narrow focus on the Bay Area. They are also high-friction (since now you just need to interview and go through the process of 8 placement services instead of cutting out the middleman and just applying to the 8 place you'd like to work) and pretty restrictive in their interpretation of candidacies.
These (and probably most) services are currently geared toward technology hubs and in-office work, that's true, as that's still the norm in industry, so they reflect that. I'm in NYC and saw plenty of outreach.
For remote, remoteok.io seemed pretty good when I used it.
