This is such a un-nuanced take.
In this case Firefox's route-to-market is the product. It's a distribution channel where some people who receive the free version will upgrade.
Free tiers for products where some will pay to upgrade seems like a reasonable compromise, but it does depend on how the deal is structured.
If Mullvad pays Firefox for the free users then Firefox's incentives are aligned with its users.
If Mullvad pays per conversion then it's a different story.
The other aspect is I expect it would stain the IP pool further. VPN IPs often end up on various blacklists due to abuse and introducing a wave of free users would only make it worse for paying customers.
[1] https://mullvad.net/en/pricing
> Why no free plan? "Free" services nearly always come at some cost, whether that be the time you spend watching an intro ad, the collection of your data, or by limiting the functionality of the service. We don't operate that way – at all.
From OMG Ubuntu
It's still correct though. In this context Mozilla uses the firefox-users as their test and demo base. At the end is commercial benefit.
And I think the core criticism still applies. Mozilla gave up on the browser years ago, let's be honest. It may be interesting from a historic point of view to find out how, when and why, but meanwhile the rest of the world has moved on already, so ...