You make it sounds like it's the norm and pass it as a valid argument but it does sound more like a passed down urban legend, not even personal. Or what went on is something more like "a buddy of mine contacted that big agency for their small one-page website and he was told they don't take projects under 200k because they work for big clients and big complex projects, lol can you believe they ask 200k for a small website?" and that became "agency asked 200k for small website" anecdote.
Anyway, this anecdote doesn't fit with the field and it's at best a really rare exception, not representative and not relevant. So I found it dishonest to bring it up like that in this context.
Then there are others where you go pay 10k and get a WordPress spaghetti that no one else is willing to take on because it just is done completely out of standards of WP.
So how do you as a small business owner even know whether the agency you pay 10k is giving you good and maintainable code?
in 2 years when you want changes you'll realise that no one wants to work on this or if they do, they will ask much more, and the previous agency might be willing to take it on, but they will have the leverage to ask even more.
I don't know about dishonest, but it's ludicrously unrepresentative when there are tens thousands of agencies that specialise in doing quick one pagers or ten pagers for very little money, sometimes as a loss leader to try to sell them other stuff.
It's like insisting that you won't get a car to take you to the supermarket for less than $200k based on experience of enquiring about the availability of cheap runarounds but only at supercar dealerships
Think most of them use WordPress, which may or may not fit into people's ideas of page builders. tbh most of the OP's criticisms about composability and maintainability and feature completeness don't really matter for five page sites anyway, but an agency using a CMS template likely has the advantage of having some idea how sections and inheritance etc work, and more design skill in creating and using building blocks than the DIY-er.
And if you actually need something hand rolled using authentic vanilla HTML and artisanal node frameworks you can still get it for less than $200k :)
Anyway, this anecdote doesn't fit with the field and it's at best a really rare exception, not representative and not relevant. So I found it dishonest to bring it up like that in this context.