Except this isn't true. 2022 saw 311.9 million visitors, up from 2000 which saw 285.8 million. That's not "huge" growth, that's not even keeping up with population growth (2020: 329 million vs 2000: 282 million). https://www.nps.gov/aboutus/visitation-numbers.htm
For example, Smoky Mountains NP went from 8M in 1980 to 10M in 2000 to 14M in 2022.
Zion went from 1M in 1980 to 2.4M in 2000 to 4.7 M in 2022.
Yosemite went from 2.5M to 5M+, much of that concentrated in the Valley.
For the impacted parks, it is very difficult to keep up with that sort of growth. It's not like those parks grow bigger to keep up with visitation, or hire staff at the same rate, or are able to build more parking lots.
Edit: And also, for Wilderness-designated areas -- whose purpose is to provide a "wilderness feel" for current and future generations, as distinct from the "crowded Yosemite lodge feel" -- it's an even tougher ask. There are only so many trails you can build through a glacier or a meadow or a ridgetop before you erode the wilderness feel completely, and it's hard to spread groups out enough on those few trails so that they're not swarming past each other.
Yosemite is popular and began to use mandatory busses. That seems reasonable, though unrelated to the topic of junk website fees.
Buses are one step, but not always enough. Zion for example has mandatory bussing but they still need to do permits for Angel's Landing (if I remember right) and lotteries for the Narrows, especially for the few backpacking campsites in there.