I mean, tables can do what they want, but clearly, they miss out on some things by sticking to official all the time. For me personally, I am all for a mix of Official and Unofficial/3PP to accomplish things that normally the official stuff wouldn't let ya do.
Example: In 3.0/3.5, if I wanted to play an Awakened Canadian Goose paladin whose main objective in life was to slay the evil Red Dragon that was plaguing the valley it lived in, I'd have to find stats for Canadian Geese and then deal with the appropriate stat modifiers and all that crap while contending if it wasn't absolutely useless. For 5E though, all I need to do to accomplish such a goal is to use 3PP setting material, such as Humblewood, and some refluffage later, BOOM: I have a Canadian Goose Paladin that is awakened. Without having to jump through a crapton of hoops or worry about being absolutely useless to play as. Going by the official 5E route, I really don't have a "Goose" stat block to use in the monster section.
If I wanted to play 5E DOOM: Then I just combine the use of the 3PP settings of Carbon 2185(5E cyberpunk) and Return to Planet Apocalypse(Fantasy DOOM 5E.). Now I have Hackers blinding demons by overloading their optics with a crapton of Spamware/Ads/Malware as they sic their Drone pet to carpet bomb them as a Sniper from the rooftop is providing covering fire against a Cacodemon.
Sure I could use both the official cat stat block and the wolf stat block along with the Tasha's Sidekick rules, but with the use of Animal Adventures, which again is 3PP rules for playing as Cats and Dog pcs in 5E, I just don't have a Sidekick character. I have a Black Cat Warlock eldritch blasting devils/demons back to hell, or a Rune Knight Grey Wolf that allows me to play out my Dark Souls dream of playing as Great Wolf Sif. Heck the 5E Blue Rose Adventurer Guide can even let me make a Giant Centipede Battle Master if I wanted.
I can play as a Drider which is something that is not officially supported by WoTC and doesn't require me to somehow reverse engineer the stat block. Win Win! (Although I kinda chuckle at the absurd dancing around the subject answer it gives for Drider sizes for the playable race version.)
www.drivethrurpg.com
I don't have much experience with Homebrewing. So a great number of unofficial/3PP that's out there for 5E really helps for that. If tables/DMs want to Homebrew stuff and work together to make something, there's nothing wrong with that too and I can see how fun it can be. I'm just saying that strictly adhereing to Official/Adventure League only can make some players/dms miss out on some great stuff.