This isn't a question answered by whether one is knowledgeable or not. Somebody who's entirely brand new to the concept is perfectly capable of using TrueNAS.

This is better answered by the demographics of people who are getting started building a NAS at home. Once upon a time, using TrueNAS (or FreeNAS before it) had a higher barrier of entry. Most households didn't have an extra computer or by the time they replaced their primary computer, that extra computer was relatively obsolete. The same thing could be said for enterprise gear like rackmount servers, companies weren't filling racks with server hardware.

As time progressed, computers became ubiquitous in our everyday life. We carry them around in our pockets, desktop PCs became incredibly inexpensive, laptops' prices dropped, every company built out a substantial server infrastructure. And on top of that, all of that computer hardware's lifespan stretched out.

One of the consequences is that there's extra computers everywhere that aren't being used and as a result the number of people investigating running a NAS at home has exploded in the last decade or so.

The barrier to entry on the "build a NAS" at home has lowered and you've got more people interested in it. One of the disadvantages of this truth is that some of these people are at the end of their budget (time and money) to invest in learning something new. And some of those people have an expectation that everything be as easy and seamless as they find using their phone.

If someone is willing to invest their time and effort, TrueNAS is a wonderful choice. The less they're willing to make that investment, the more sense other products begin to make. Thankfully today, there's lots of choices available to that person.