Gary Illyes from Google, a webmaster trends analysts whose job is to help webmasters with communication, said on Twitter that typically, but not always, Google employees only help or step into the forums when they need to.
So if you go to the Google forums for help, the chances of a Googlers actually helping you directly is slim to none.
The exception throughout all these years is John Mueller who does proactively respond to threads. He might not do it daily but he does go in frequently and respond. It is unclear to me if those threads are being flagged by top contributors or not.
Either way, Gary's statement for the most part is true. Googlers won't typically proactively respond to threads in their help forums without someone outside of Google calling the thread out to them. This is not always the case, but I believe it is how things are run most of the time.
Forum discussion at Twitter.
