I use a Garmin and Strava.
Both have ways to hide your “home” location:
Understanding Privacy Zones in Garmin Connect
Strava Privacy Zones
I have read these settings do affect CityStrides, as it no longer has good data, near your privacy zone.
But, I always figured this is the area you are going to finish first, or probably already have, with your first big sync, so a privacy setting won’t have much affect on street completion. Going forward, you likely already have your home area done.
I don’t use the settings, but have read they too create a blob, that more or less identifies your home area. This is what @fredrik.coulter is saying.
Not sure about other sync options, but at least for these two, it’s not really needed at CityStrieds (unless I’m missing something). Need to check MapMyRun and RunKeeper for similar settings (for my own curiosity). I’ll edit this post with what I find.
Edit: Well if MapMyRun and RunKeeper have a similar setting, it’s not as obvious.