Has there been a breakthrough in film technology for television?

It's unclear what you're comparing it to, but yes, there have been tons of technologies that have either come onto the scene or come down in price significantly over the last 30 years. Shooting on digital allows many more options for the filming, editing, and post-production portions of television shows. Digital cameras produce better quality output than the video cameras of yore and at a higher resolution. There are inexpensive cameras that shoot in log and even RAW formats at 4k resolution. And having a full editing suite with color correction, compositing, etc. is now only tens of thousands of dollars instead of hundreds of thousands to millions.

Digital also allows for much faster turn-around, which makes some things possible that were not before. Back when the original Star Wars movie was filmed, for example, all those composites of space ships flying around shooting at each other were filmed on film and then optically composited together. It was a laborious process. Now they can either film on digital, or create objects completely digitally without filming anything, and get very good to perfect composites. (By perfect, I mean not having to deal with variations in lighting on a green screen, etc. It comes out of the computer already matted the right way. Whether it looks good is another issue.) The software to put together foregrounds and backgrounds is easier to use than doing it by hand. (If you've ever watched the original Battlestar Galactica series, you'll notice there's only about 3 shots of the spaceships shooting at each other and they get reused over and over again, sometimes flipped to make them less monotonous.)

Back in, say, the 80s, it was unlikely that you'd do a lot of color styling of a television show because it was expensive to send the film out and to hire a colorist (or color timer as they were called then) to do the work. Now, every shot can be styled however you want and it can be delivered very quickly because there's no film to expose. You can either add color filters right in the editor, or send your footage to another app to adjust the colors and send it back to your editor for further processing and cutting.

And very popular shows are getting larger budgets. 1 season of Game of Thrones has about the same budget as a mid-size movie (about $6 million per episode for season 1 and looking like about $15 million per episode for season 8).

So all those things together make for some really compelling TV shows! Better equipment used to film it, faster turn around for complex things, better tools to edit and do other post-production stuff, and bigger budgets.

All of your question are right. First, thanks to digital cameras producing of "for TV" materials are cheaper. When making a serial for TV companies were using film with different film grain.
Second, because of the production time and costs the locations were usually filmed in studios reusing old scenography and avoiding "unnecessary" scenes (for example instead of showing moon landing they used some old documentary or just told about that in conversation). And because it was all made in studio the lenses where preset for such scenography and lights were all figured out for all the production using the same studio/cameras.
What influenced the change? Mostly Top Gear by BBC. The production cost of one episode was justified by the "selling" value to other tv stations. It turn out that investing in filming on locations, with new camera lenses, angles and cameramen's that knew what filter is would yeld a higher value in final product.

Then, time of post-production. Usually series, like Friends, are made during the show time. So the last episode isn't ready when the first one is aired. So there was no time for creating CGI, detailed costumes and special montages.
Also costs: creators could get stopped mid season if the views were low so producers would not loose money. It stopped them from making risky investment or just pouring a lot of money in the production from the start.

What influenced the change? Netflix, they identified the "binge watching" and made material for that audience. So there were no time reason to slow down production to match the airing time if the airing time could be one day. Also, for Netflix there is no hiatus time or "September start" so they can put out series whenever they want. So they could made a series just like a movie similar time and effort and release the product "when it's done"