When it's still enough runway to trim it down, there's often still some hope of greater success - and a VC investor might believe that it's more valuable to have a 1% chance of it becoming a unicorn or a few percent chance of arranging some last-minute buyout, rather than pick up the 100% certain but low price it has as a non-growth business based on its revenue.
Yes, due to their large bankroll and diversified position, VCs can afford to be risk-neutral and only care about expected returns. Founders and employees obviously cannot be risk-neutral, ergo startups are a great bet for a VC and a terrible bet for anyone else.
I don't really see why such a side deal would be possible - if the VC goal is to get the founder-manager to try for that narrow hope of few percent of major success and discourage them from settling for a lower-value stable business, allowing the founders to cash out would be counterproductive, it's in the VCs interests to ensure that founders personal financial motivation is aligned to theirs, that the founders are also motivated to go big or go bust.
In essence, if the startup is slowing down and perhaps not going anywhere, then the standard existing deal with founders where the founders can cash out only if they enable to VCs cash out at a profit (for example, if they manage to pull out all the stops to make a failing startup look attractive to some bigger fool) is exactly what VCs want, and in such a situation the founders have no leverage to extract a compromise that's worse for VCs.
The typical situation is the company has been around for a few years and the founder has some reasonable sounding expenses. Then the next round includes some cashing out as new investors join.
What to you (and pretty much anyone else) looks like a business that just needs adjustments to reach profitability, to the VCs it's profile maintenance work for little relative benefit in the long-term. The chances of that company turning 10-20x profits in the next few years is basically zero and they just cut their losses (in their view).
