The Meaning of Life, the Universe, and Everything.
People have lives. There are x64 faithful-esc packs out there updated to 1.13, but with their fair share of bugs and incomplete textures. 1.13 completely overhauled how block, mob, and item ids work, which requires every texture file to be renamed to even be recognized by the game. It sounds simple, but having to update hundreds of file names takes time and isn't the most fun task. And that's before most people decide to start texturing 1.13 items and blocks and mobs. All these artists have real lives. Jobs, school, friends and family, which become the priority, and justly so. But just because people have lost time and aren't updating as frequently does not mean that said pack is dead or the game itself is for that matter, though there is another thread for that. My advice would be to either wait or consider other resource packs if or until the packs you're looking for update.