It is difficult for us to estimate the size of the user base accurately
How does opt in telemetry solve this? You only get that information if everyone opts in, surely.
The only correct way for them to have done this is to tell the users "Hey, we want to know more about usage like what platforms you run on and trouble the software has. We'd like your feedback on whether you're good with this or not and if you are what kind of information would be acceptable to you" and to say this long before it was implemented.
The only reason to spring it on people like this is if they want to take technology from the software and sell it off to another company.
So predictable.