Sure. One may be curious within the orthodoxy, but that is t what was brought up in the OP. In the context of keeping what works and discarding what doesn’t… orthodoxy is actively antithetical to that goal.
In a broad sense, this is true, but it's more nuanced than this.
Firstly, this assumes folks' direct and primary interest is in simply learning fighting skills. I'll agree that's a part of it for most folks, but if they chose BJJ or Karate or Boxing or whatever, there's a reason. Part of that reason usually has to do with their interest in that specific style. That interest may be because they think it's "the best" (or at least "the best" at some context), but it's my experience that most folks are interested in it because of how they perceive folks in that style. When I started in MA, Karate was exotic, so studying "Karate" (which term, honestly, included all eastern MA, for the uneducated looking to start) felt cool. So a bunch of people got into it at least in part (meaning pretty much any MA that didn't wear street clothes or boxing shorts) because it felt cool.
Sometimes that perception was just the mystery of it. Something seemed different from what they could directly understand, so they wanted to find out about it - they wanted "in". Boxing doesn't have that sense of mystery - most of us can right away figure out how to punch, and have done so without any training (though likely not very well), but it's unlikely we palm-heeled, chopped, or threw a side kick out of instinct.
And once we found that thing that interested us, part of the interest was learning how to work within it. Like trying to figure out how to play pretty music only in minor keys. It can be done, but it's a bit harder than in a major key.
Now we get to the absorb/discard. I love to work within the bounds of NGA as I perceive those bounds. My perception is distinctly different from my instructors'. Much of what I trained and taught was very "traditional", in the sense that I kept much of it as close to what I was taught as possible. The challenge was to decide which uses of those things were least useful, and discard those - then to find things in other styles that mated with the core of the art (so fit the traditional approach) and absorb them.
I think strong instructors in traditional arts tend to do a lot of discard and absorb, but it's hard to see unless you're familiar with what they've seen. I'd look at TKD forms from several instructors and never see where one of them had discarded some things that had crept in and interfered with how the principles are best taught; or had found better explanations than they received, and absorbed those into their teachings.
But, yes, those of us looking to adhere - even somewhat - to tradition will definitely discard less and absorb less than someone who decides to abandon (not using that term derogatorily) the tradition and freely adopt whatever works best for them. And there are systems with less tradition in them (BJJ vs Judo, for instance), and those systems will more readily adapt and adopt, and will also be less recognizable over time.
I'll also point out that the absorb/discard process should be happening for every student within every system. There will be things that are effective for "people" that won't be particularly useful for a specific person. They will learn that, but discard it from their personal set of go-to techniques - the techniques they found useful and absorbed into that set.