Yeah, I am late.
Before BR experience was a thing, there were (and still are) a group of players that like to run endurance and invite people off their friends list as they logged in to join in the mayhem. I used to complete several times a week in Stonewood, Canny, Plankerton and Twine either with an endurance I started myself (most often) or joining a friends in progress.
The problem with endurance is the time investment. Not just the 2 hours to finish it, but the build and test time also. Even if a player copies a build from YouTube you are still looking at a huge time investment to build it, and likely several runs to perfect it.
Stopping people from inviting friends after wave 2 is not the right answer to fix the problem of organized leeching for BR experience, which I am willing to bet most of the hard core endurance builders don't even care about.
It was much easier to have a fun, social gaming experience when you could grab friends as they randomly logged in. That is gone now and replaced by a situation where 4 players have to set a date and a time slot of 2 hours to go do endurance. I would imagine that is not happening very often.
How about giving 50% rewards or something along those lines? Or perhaps open up the window to join until wave 20-25. I don't know, I don't design games. What I do know is what we have now is awful.
I feel like the people that run that were running this purely for the BR exp likely for the most part really don't care about StW. That to me makes this change a slap in the face to the people that do like and play StW exclusively.
I accept that maybe I am in the minority, I don't really know.
Source: https://www.reddit.com/r/FORTnITE/comments/wh88c5/about_those_changes_to_joining_endurance/