I used to bike from Herndon to my former office in Loudoun, VA. The W&OD bike trail is fantastic. It was a beautiful ride, up until the last few miles getting from the trail to the office park at Loudoun Station. The most direct route is to ride on the shoulders of Loudoun County Parkway in front of the Verizon building. There are no sidewalks, the shoulders are littered with gravel and cars drive around 50 MPH. Just, no. I had worked out a path that added about a mile but kept me either on sidewalks or side roads. I understand the argument that sidewalks are for pedestrians, not cyclists, but there are very very few pedestrians on those sidewalks. Loudoun really should put a path from the Station to the W&OD trail before the Silver Line metro comes in.

To be fair, it doesn't seem like the developers could/should be installing sidewalks on land that isn't theirs without coordination with the landowner (so they have to end the sidewalk at the edge of their land).

Well no, the city should be requiring that developers build sidewalks on the public right-of-ways next to the roads.

That makes sense and is how it's typically done up here. I read the GGP's post as a complaint against the developers not against the city/country/AHJ, who is the only one in a position to make the change (granting public right of way, or taking property via eminent domain as needed).

It was meant as a complaint against the county. They have a silly rule in place - developer must build sidewalks. That's it. No coordination between developers/land-owners. No plan to link developments. See the sibling comment about Loudoun Station - a large mixed-use development that isn't linked to the largest bike trail in northern VA.