Open-source is becoming the only way to develop (and, especially, maintain) complex software. The fact that the engineers can gain employer-independent reputations gives them an incentive that's astronomically expensive (as hedge fund compensation goes) to replicate otherwise.
The world is finally figuring out that it's impossible to employ top talent, but that it can be quite lucrative to sponsor it.
So is, "Open-source is becoming the only way to develop (and, especially, maintain) complex software". This is hyperbole. Complex software has been developed and maintained for over half a century, in myriad ways.
Top talent has access to thousands of other well paying roles. You cannot treat them the same way companies treat regular employees (badly). If you give them pointless work, or work without career growth, they can up and leave in a heartbeat. If you try and bully them or pressure them to work long hours or place pointless restrictions (dress code, start times, vacation policy, etc) on them they will leave.
That is a statement I think most people on here would agree with. The original statement wasn't. A company can be a joy to work for. You can also make some really good cash.
In technical fact, not impossible but, in fact, common. In spirit, you don't really employ top talent, in the sense that subordinating it wastes it. You sponsor it and become a beneficiary of it.
Perhaps the OP meant to say it's tough to retain top talent without being on the top of your own game in terms of providing benefits and culture to them.
The world is finally figuring out that it's impossible to employ top talent, but that it can be quite lucrative to sponsor it.