Yet, no one notices when business opportunity stares them in the face.
Go and duplicate screenhero. It's not that hard (Screenhero was written by 4 devs and 1 designer). They did YC in winter 2013 and got acquired by Slack in Jan 20015, so it's less than 2 years.
You have a validated product that many people love and are willing to pay for and enough of a "outside of Slack" market to sustain a small company.
On launch you'll get free PR just by announcing "Screenhero alternative".
And if you do a good job, it's likely that Atlassian (or some other Slack competitor) will want to acquire you for a tidy sum.
Lot's of the hard code has been written for you (libraries for stun firewall traversal, vp8 for the video codec). You need to write a simple backend for matching people and 2 desktop apps (mac and windows).
It's not easy but it's also not a problem that requires breaking new ground, just solid engineering.
What we get instead are pleas to Slack to not kill stand-alone Screenhero and bemoaning that someone didn't write OSS (aka free) clone.