A couple years ago I worked on a project that tried to put a 40+ page printed form online. The form is complex. The form has a lot of intricate guidance and notes, and sections that must or must not be completed based on previous sections or fields.
I threw together a form builder by re-purposing old code from a side project that took me two years to polish. My proof of concept let an admin change guidance on the fly, without touching HTML. Fields could be re-sequenced, data types changed. Business rules could be linked to fields dynamically, and applied to single fields or entire form sections. Data was saved to a SQL Server (already in wide use in the estate). My proof of concept took 4 weeks, and on the basis of that I estimated a 6 month project. When I presented the idea it was viewed as being too complex, and therefore too risky.
So the dev team just started hacking it out, field by field, and saving the whole form into Mongo as a single, nested document. Guidance was hard-coded into the HTML. It was fast, and at the start everyone was awed.
Of course soon after the customer decided that the guidance for the printed form wasn't appropriate for the online version. And of course the customer wanted to analyse data across all forms. What was a 6 month piece of work took 3 years. And still no ability to analyse data nested in Mongo documents. Any change requires hours of re-work, regression tests and sign-off.
All because agile.
In my 20's I'd have been emotionally destroyed. Ego like an aeroplane into the side of a mountain. No survivors, call of the search. Happily I'm in my mid-40's. I know better, and I know better than challenging an inexperienced project lead that has too much authority. So I move on. There's always a project that's more suited to my style of work (slow).