Please allow me to apologize in advance for the long rant that is to follow.
I think you're proving my point by insinuating that I need to put forth a way for Mozilla to find non-ad and non-Google revenue streams, and I also think you're misunderstanding me by implying I'm putting forward an emotional appeal -- I actually could care less about whether or not Mozilla Corp chooses to uphold the open source values that propelled it to success and relevance, I merely think it's poor decision making to ignore that if they wish to survive.
This, of course, was the heart of the question I posted to you at the end of my comment, and it is also something that you still haven't answered. Let me reiterate it: what is the key differentiator of Firefox? Why do people use it? You are talking about why you don't think it's a big deal. The thing is, whether you (or anyone else) thinks it is a big deal or not is simply not directly relevant to Mozilla and Firefox (although it is a signal). The question of whether it's strategically a good decision for them is actually important. I believe that it is not. To further illustrate that, let me make some arguments by comparison.
Is Python ad-supported? Is the Linux Kernel ad supported? Ruby? Nginx? There are companies that make products which utilize Python or are greatly involved in the Python ecosystem, and those companies contribute back to the ecosystem because it serves their purposes. Likewise with the Linux Kernel, Ruby, Nginx, Python, and many other excellent pieces of open source software. Would you dilute the reference protocols and implementations for these products by diluting key parts of their functionality with advertising in a form that is essentially malware?
No. You wouldn't do that because it would compromise the trust of your core users and ultimately result in negative momentum. You wouldn't do that because ultimately, it's poor product management. Healthy businesses that operate with a division between the open source and closed source areas are well trodden territories, and one of the easiest ways to kill the healthy business line that depends on the open source product's mindshare is to dilute it. This is what you're not addressing, and based on your arguments, it may be something that you don't understand. What Mozilla Corp just did was a bafflingly poor product management decision. It was an experiment with little reward and what appears to be high risk. Time will tell. They may have lost sight of the the need to add value first in order to rake in profits long term, and the need for that to sometimes take longer, more expensive paths to result in the most lucrative circuit.
This, of course, is something that the original core contributors to all of these projects understood quite well. They produced software, but they were first and foremost constructing protocols. Protocols can be created in purely informational theoretic terms and be released into the wild, and upon critical mass of mindshare adoption, operate self-sustainably in their current form. It is certainly the case that money and other resources can scale up the rate of development and scope of these protocols as well as the ecosystem around it, but it is not a requirement. The organization and labor that construct these protocols are motivated by a variety of motivations, but often times, one of the core motivations is the desire to mutate the way that things flow in societal infrastructures by improving them. When attempting to build one of these mutations, focusing on profitability prematurely is ironically one of the easiest ways to doom it, or precluding it from ever occurring. It will get you stuck in local minima and distract you from executing correctly. Why did Google beat every other search engine? They figured out how to do search properly, better than every other competitors.
Mozilla Corporation (if it can) needs to figure out how to do the browser properly, better than every other one of its competitors. If not, it will slowly fade into obsolescence as superior forks or competitors better at its core functionality supplant it.