Absolutely.
It is valuable to TFP as a soft launch and quite frankly as a rewarding weekend for them to sit back and watch people who love their creation play and give spontaneous and candid feedback while they are in the midst of playing. The developers often get involved in the chats of various streams and talk directly with the playerbase as well during the weekend. There are always positive things that come out of the streamer weekend that end up benefiting the game for everyone.
It is valuable to the streamers because it is an exclusive event. They are assured to get more viewers than they would if everyone was busily playing it on their own. That is what attracts them from a business POV. Of course, they are also fans of the game so they are also excited to play the new build.
It is valuable to the player base because it does attract attention to the new release and many who may not have realized that A20 was about to drop and who may have had it uninstalled for a year or more will re-install it and dive back in to check out the new build. If the game is not installed then you get no notification from Steam that there has been an update. It also will bring in new players. Some of the streamers haven't been playing 7 Days to Die recently so their viewers are those who came for a different game and stayed because they liked the influencer. Now they will see 7 Days to Die possibly for the first time and get intrigued. New players and a larger player base is good for all the players.
The way I think it could be super valuable is if Laz works all night long Sunday to switch up all the traps and jump scares he designed into the POIs from the way people watched the streamers encounter them to something different and unexpected. Come on Laz. Don't be lazy.