It's "easy" when you have hundreds/thousands of people willing to work for free for hundreds/thousands of hours.
You mean like the Loz fan base or the paid professions that released an HD Zelda teaser for the Wii U over five years ago and had a playable BotW demo for over three years before release?
Look the point simply is bad design decisions were made and constantly revamping the project over a period of five years, it's $100,000,000 cost had pushed people towards the
get it the f**k out the door now option. You can play Nintendo/Zela fanboi and irrationally defend it until the end of time, see next quote, but BotW was released to recuperate losses and it was bundled along side an early Switch release rather than waiting for the traditional Mario game, for much of the same reason. Nintendo needed to cover losses and someone said now instead of listening to another it'll be out soon promise. And like it or not, the game is just going to serve as beta test platform of the new gaming engine and world psychics for the later, and far better, Zelda game coming in the next three years will make usage of.
Hell, BotW it's self is disgusted with it's lack of monsters. Honestly you could merge four shrines worth of effort together with some monster filled rooms/halls for thirty more traditional Zelda like dungeons. But along the way someone was like these monsters suck ass, so let's split things into four times the amount of dungeons and give one quarter the rewards hoping the player forget they only used one enemy. And that one enemy isn't even palette swapped, just equipped with different weapons. In a game where the player can just toss new weapons to any enemy they want. Zero substantial effort was clearly made in that area, and
probably it's because someone at the last minute told them they needed more points of interest on the map because Skyrim had another two or four hundred more than test build currently did.
Also public PSA for those of you running the new patch Nintendo told you would make for a better experience. You can only farm 20 arrows from mounted archers. But that's ok, since they didn't code the save flags for naked island correctly you can travel to the shrine, glide down to the chest of arrows buried in the water, loot it, saves, and simply reload your file to reloot the chest again. their looted state is never saved, so reloading the save file will reload unlooted chests allowing you to endlessly loots, save, reload, over and over again.
Skyrim did not run smoothly at launch. When you add a dozen mods from different people you'll be lucky if it doesn't crash outright.
That'd be the blind fanboi rebuttal right there"
"Yeah well, I downloaded a bunch of shit mods from a bunch of terrible people on Skyrim and it didn't work so well. So logical conclusion is BotW must be better!"
Finished PS: Torment.
How long did that take you O.o
Edit - Less than six days.