No one is forcing you. You have a group of people who arbitrarily decided delves are required… if you actually even get a decent piece to use, from the vault slot. Also, only so many pieces you can put in the cataluyst, too.
You do not need to do delves to unlock any content.
You make (or in this case, agree) to the choice.
Just because you want content to work a certain way to make you feel better about being “forced” to do delves does not mean others have to agree.
Or - an this may be a radical idea or concept for you - maybe you can just be happy that there are more options to help you get hero level gear so you can progress through content faster, rather than complaining about it.
Again, your game experience is not everyone’s game experience.