But you’re right: too little, too late.
Why was that important? I was under the impression that exe and msi installer had no real difference between them. Obviously I am incorrect but I am wondering why.
In Windows there are further nuances, such as installing per-user, per-machine, or both. Similarly, MSI support often implies support for transforms (MST files) and patches (MSP files) also, which is important on large networks. Back in the days of constrained bandwidths, MSPs were great for rolling out updates without killing the WAN, but few vendors would provide them.
Firefox tended to prefer the interactive install wizard installers and hence deploying it at scale was an enormous pain in the arse.
For example, the Enterprise CA thing actually interacted with the packaging. You had to crack open the Firefox files, download some obscure NSS command-line tool that they regularly moved around on their website to spite admins, and inject your corporate certificates into the Firefox-specific Root CA file. After this, everything had to be put back together in some way for deployment, typically by repackaging the files into an MSI.
Similarly, instead of ADM Templates that allow settings to be pushed out via Group Policy, you had to do hideous things to JavaScript files. These also changed regularly and had all sorts of limitations.
There was just no way anyone in their right mind would do this every few weeks to keep up with the Firefox release schedule. IT admins have other things to do, not just babysitting Firefox, the one special and unique flower that refuses to play nice with Windows.
The only other obstinately anti-admin products I can think of that were this bad were the Java Runtime and the Adobe suite of products. Even Adobe provided an ADM template at least, even though they published it as a PDF.
I am sure there are other reasons, but these two are the important ones.
Thinking it is a good idea to leave Windows users behind. You don't hurt Microsoft by doing that, you hurt yourself.
In the enterprise world, Firefox lacked a few, small, but critical features:
1) MSI Installers
2) Group Policy Administrative Templates
3) Proxy configuration from Windows
4) Enterprise PKI integration
Some of these are supported now, but for about a decade there was at least one person in Mozilla with a philosophical opposition to doing anything that is seen as helping an enterprise Windows network deployment.
I'm pretty certain that Firefox still doesn't work properly in a large corporate environment. At any rate, I've given up trying, as have millions of other administrators. We installed Chrome, which "just worked", and moved on.
The result of this is that enterprise web applications were written for Chrome, not IE or Firefox. Chrome became mandated and automatically pushed to every machine. It has become the new IE6, for better or worse.
Firefox missed that boat.