Standards evolve over time. The Mac was not the first GUI and neither was Windows, Solaris, Irix, Amiga, Linux (various) etc. Yet almost everyone in the industry solved the problems by going in approximately the same direction while Apple stubbornly stuck to their convictions.
No problem with that at all. Being opinionated is fine. No issues there.
One way to look at it is that Apple, as a computer company, was a failure. They were on the edge of becoming insolvent. In fact, most Apple users don't know that Microsoft/Bill Gates rescued Apple from meeting an unsightly end by investing $150 million (maybe more, I don't remember) into the company. This would be equivalent to a billion dollar+ investment today.
What saved Apple was the iPhone. Plain and simple. The computer portion of their business was crashing and burning. Note that I am not ascribing this impending doom to the choices made for the GUI at all. Just reviewing some history.
Sometimes being very different is cool, and sometimes it isn't.
Let's look at it from a very different frame of reference. All browsers today work and feel about the same to a casual user --the general public. If someone insisted on delivering one that behaved and looked very different from the standards developed over time, they would not find a great deal of adoption. Microsoft did the right thing in dropping their failed browser and adopting Chromium. That is an example of a good decision made based on how standards evolved outside of their own efforts. Late, sure, but they were opinionated about browsers and eventually understood they were wrong.
That's what Macs felt like to the rest of the world. Weird. Perhaps unnecessarily weird. As the world was getting used to having a capable computer on every desk, Apple, in my opinion, continued to shoot itself in the foot by not listening to a user base 10x to 100x the size of their at all.
You can do that, of course, but when your company ends-up at the edge of failure and you have to be rescued by your competitor...maybe it's time to rethink your approach.
Apple insisted on silly things, like having a single mouse button and, yes, a single menu bar. As I said before, the single menu bar makes sense for some single small screen use-cases, but it quickly falls apart once you go big and multiple screens. There's also the effect of having multiple windows belonging to multiple applications strewn about your screen or screens with no clear association to a single application. I remember the early days of this. It was a mess. The difference between running something like Photoshop on Windows vs. a Mac, was night and day. One was clean and organized. The other was a mess of windows everywhere. What I am using for this use-case evaluation was the reaction of my daughter who had been learning tools such as GIMP and Photoshop on a PC and then saw how Photoshop ran on a Mac. She wanted nothing to do with it.
Anyhow, I am not here to downgrade Apple computers. They are fine. Very usable. Lots of people love them and, in my opinion, pay ridiculous amounts of money for them. All I am saying is that Apple could have made an effort to still be opinionated while giving users the choices they were already making elsewhere. That's an important point. The PC world has been an amazing experiment from day one. For the most part choices were made by users. There have been massive failures in that universe. Users voted with their purchases every step of the way. And that's how we got where we are. Were it not for Microsoft/Bill Gates and, later, the iPhone, it is quite possible the Mac would have died long ago. This was a technology imposed on users from above. I think I can say it is very rare to see that kind of thing survive in the long term. I still remember when Apple decided to move away from the PowerPC platform and killed off every customer's investment in software. In the PC world, like it or not, the issue of compatibility across transitions was incredibly important, hence the slow-but-steady evolution rather than having radical step changes in technology.
To some degree I equate some of what Tesla is doing to this effect. Today, if you analyze their financials, Tesla would be out of business if they had to rely on car sales. A harsher way to put it is that their electric car business is a failure. Had it not been for carbon credits they would have imploded, or, at the very least, would have had to raise tons of capital to burn for a few more years. The truth is simple: As much as I like electrics, nobody wants them. Not at scale. And the reasons are somewhat similar to the Apple issues (if we contort thing around). If the GUI, other platform choices and cost are relabeled as "infrastructure", the electric car isn't desirable to the vast majority of the population due to infrastructure issues. There are approximately 1.4 billion conventional cars in the world vs. about 10 million electrics. If you look at the energy required to replace the fleet of IC cars (to manufacture the cars, batteries, charging stations, etc.) and the massive step-change in electric power generation, it is very easy to conclude the idea is far closer to ridiculous on any time horizon shorter than 50 to 100 years.
Anyhow, it's a fun bit of computing history.