I can agree with your assessment that Dorico hasn’t become the ‘standard’ as of right now in some parts of the industry. I can also agree that Dorico is a great tool with many amazing features.
I believe that the issue is merely a saturation of the market. Finale has been distributed in America since 1989/1990, 30+ years (please correct me if I am wrong). They have a TON of users. Some of which are 30+ years into using it. Sibelius was introduced in America around 1998, 25+ years. Sibelius did a GREAT job of reaching out to schools and educational institutions to get people into the Sibelius product line. And now Sibelius has a TON of users (arguably more than Finale). Dorico has been on the market for 7 years. They are in the process of trying to get into schools and other educational institutions to build the user base. This process takes time, and you have to have institutions willing to support BOTH packages, or all 3 packages if they have an established user base. While people that use Dorico agree that it is great, you have to get the product into more hands.
Sibelius became somewhat of a standard, not because it was instantly adopted. It took many, many years of getting students to use it, who then became professionals, who then pushed their friends and colleagues to try out Sibelius. To then have more future students use Sibelius, by default FORCING the user base to grow.
When it comes to a subscription model ($10 per month, versus $100 per month), I can tell you that I would rather pay $250 a year versus $10 a month. I have paid for software on a subscription basis, and the improvement in the program was minimal. The other issue is you are ALWAYS forced to stay in the ecosystem, something I am not a fan of. If Dorico died tomorrow, I would have software that I can use. If Sibelius died tomorrow, there could be many issues since you would need have code that would need changing to allow the software to work without subscriptions. Professionals will pay the reasonable cost for tools they need, if the tools really help them.
I say give it time. I already have many friends who have slowly moved into the Dorico world. We all sing our praises, and slowly but surely, more and more people are getting into it. More and more schools will start to use it, producing more and more students into the real world using it, therefore growing the user base. 7 years is not a long time, compared to the life of the other players. I would argue with each passing year, the user base is growing.
Edit: Leo said in about 2 sentences which took me MANY, MANY more sentences to say.