I saw a brilliant explanation some time ago that I’m about to butcher back into a terrible one, bear with me:
Think about 2 particles traveling together. When one gets tugged, it in turns tugs the other one with it. This tug takes some time, since one particle essentially “tells” the other particle to come with it, meaning there’s some level of information exchange happening between these two particles, and that exchange happens at the speed of light. Think about the travel distance between these two particles, it would be pretty linear, and pretty short, so you essentially do not notice this effect since it’s so fast.
Now think about what happens when those 2 particles start going faster. The information exchange still happens, it still happens at the speed of light, but now that those particles are moving faster in some direction, the information exchange would seem to still go linearly from particle A to particle B, but in reality it would be traveling “diagonally”, since it would have to cover that extra distance being added by the particles moving in certain direction. This is the crucial part: what happens when those particles start getting closer to the speed of light? Well, the information exchange would have to cover the very small distance between these particles, plus the added distance from traveling closer to the speed of light. At first it’s pretty easy to cover this distance, but eventually you’re having to cover the entire distance light would take to travel in a given moment, PLUS the distance between the two particles, which…can’t happen since nothing can go faster than that speed.
That’s essentially why you can never reach the speed of light, and why the more massive an object, the less speed it can achieve: all those particles have to communicate with each other, and that takes longer and longer the closer to the speed of light the whole object moves.
See, this also perfectly explains what you’re asking: from the frame of reference of the particles, they’re seeing the information go in a straight line to them, so time is acting normally for them, but from an external perspective, that information is moving in a vector, taking a long time to reach the other particle since it’s having to cover the distance of near light speed in one direction, plus the distance between the two particles in another direction, for a total vector distance that is enormous rather than being negligible. At some point, you never see the information reach the other particle, or in other words, time for that whole object has slowed down to a near halt. This explains why time feels normal for the party traveling fast: they can’t know they’re slowed down since the information exchange is essentially the telling of time, but the external observer sees that slowdown happen, and in fact they get a compounded effect since those particles also communicate their state to the observer at the speed of light, and that distance between the observer and the particles keeps changing.
This also explains why the particles might be able to also see everything around them happening a lot faster than it should: not only is it taking them longer to get updates about themselves between themselves, but they’re also running into the information from everything around them pretty fast, essentially receiving information from external sources faster than they do from themselves, thus causing this effect of seeing everything happening faster and faster, until it seems to all happen at once at the speed of light.
Here’s the guy who made it all click for me, since I’m pretty sure I tangled more than one of you up with this long read: https://youtu.be/Vitf8YaVXhc
I host a Plex server for close to 70 friends and family members, from multiple parts of the world. I have over 60TBs of movies, tv shows, anime, anime movies, and flac music, and everyone can connect directly to my server via my reverse proxy and my public IPs. This works on their phones, their tvs, their tablets and PCs. I have people of all ages using my server, from very young kids to very old grandparents of friends. I have friends who share their accounts with their families, meaning I probably have already hit 100+ people using my server. Everyone is able to request whatever they want through overseerr with their Plex account, and everything shows up pretty instantly as soon as it is found and downloaded. It works almost flawlessly, whether locally or remotely, from anywhere in the world. I myself don’t even reside in the same home that my Plex server resides. I paid for my lifetime pass over 10 years ago.
Can you guarantee that I can move over to jellyfin and that every single person currently using my Plex server will continue having the same level of experience and quality of life that they’re having with my Plex server currently? Because if you can’t, you just answered your own question. Sometimes we self host things for ourselves and we can deal with some pains, but sometimes we require something that works for more people than just us, and that’s when we have to make compromises. Plex is not perfect, and is actively becoming enshittified, but I can’t simply dump it and replace it with something very much meant for local or single person use rather than actively serving tens to hundreds of people off a server built with OTC components.