Social circle is great for getting a girlfriend. Pay close attention to the words "a girlfriend". That means one girlfriend. If you're looking for an extended relationship (2-5 years or more), your best bet for getting that with the least amount of grief and frustration is social circle. Many men who get social circle girlfriends tend to retain those girlfriends for a long time and often beyond the useful life of the relationship. A lot of the social circle girlfriend guys are beta males and beta males operate from a scarcity mindset. It's common to see a 10 year relationship (and counting) relationship from social circle which does lead to a marriage proposal.
A social circle introduction is a higher percentage play than a swipe app interaction or approaching a stranger (either in a bar or non-bar setting). I've never had a social circle capable of providing me introductions so over the past 20+ years, I've either had to use technology or approach strangers to find dates. It's a more difficult path and it's not a path I recommend highly. Social circle is better in the shorter to medium term. You can get a solid, medium term (1-4 years) girlfriend via social circles more easily than through approaches or swiping more easily.
The problem with social circles becomes sustainability. For instance, I've lived in my current city over 10 years. Social circles have a way of getting pissed off at men who continually exchange girlfriends without marriage or babies, even if the relationships are semi-long (1-4 years). After 2 or so instances of medium term relationships, the social circle will run dry. Social circle is not likely ideal for serial monogamist who does have extended relationships but doesn't commit or the player type who tends to have relationships of less than 1 year.
In theory, you can fix this problem with relocating and re-creating social circles every so often. In practice, that would never happen. Relocations have a way of ruining social circles. Also, after age 30 at the latest, you're not getting into a good social circle in a new city if you relocate. You can get friends if you relocate after 30 but you're not likely to get a social circle that will provide you introductions to quality girlfriends, unless you can manage to be a mid to late 30s year old guy who mainly socializes with mid-20s people. That last sentence probably isn't going to happen.