It's an infinite-scroll list, it loads in 9 or so videos at a time, than it takes a second to update your scrollbar before you can scroll down further. You can't instantly jump to the last page, load all videos at once or invert the sort order. Every time you accidentally click away from the page you have to start from scratch as it doesn't remember your position, you can't bookmark it either. Some channels have hundreds or even thousands of videos. It's impossible to access them in any timely manner with the normal YouTube interface.
It's certainly not the most convenient UX, but, you know, first world problems and everything. The greatest store of knowledge almost-instantly availalbe at our fingertips, these minor UX quips are small-potatoes IMHO.
And for sure I don't think the statement "the only way to interact is via the algorithm" is accurate, when what stands between us and finding old videos is to wait a few extra seconds. That's a really strong statement compared to the reality.
Some of your complaints are valid (though they are mostly UX gripes), but this one I don't get.
I've done this multiple times and it's like three clicks. You click the channel's name, you click "videos", and you scroll down, that's it.