Ever since the first MCU film, 2008's Iron Man, Marvel Studios has included a post-credits scene in nearly all of their films with the sole exception being 2008's The Incredible Hulk with Robert Downey, Jr.'s cameo as Tony Stark instead being moved up to just before the credits roll.
Following the studio's massive success, both critically and commercially, worldwide, the inclusion of stinger scenes has been adopted by other major studios including Warner Bros. which included mid and post-credits scenes in last year's Justice League as well as Sony which included a mid-credits scene in this year's Venom. For Marvel Studios President Kevin Feige, this practice was an important one for him to include since the beginning as both a treat to fans and way to get audiences to stay and acknowledge the countless cast members that have helped make the MCU a reality.
"Movies bring people together, but they also bring people together behind the scenes," explained Feige while accepting an award at BAFTA's 2018 Britannia Awards. "At Marvel Studios, we've been putting a scene after the end credits in all of our films since the very beginning. The fans love it; it's a tease of something to come. But the real bonus is that the audience is going to sit there and look at all the names of the hundreds of thousands of people who work so hard to bring these movies to life. That really inspired me as a kid, to see all those names, and I hope it inspires people today."
Starting with 2012's The Avengers, the MCU has doubled down and included a mid-credits scene in most of their films released since in addition to post-credits scenes.
In the meantime, the next MCU film, Captain Marvel, is scheduled to open on March 8, 2019, presumably with its own mid and post-credits scenes.
(via Digital Spy)