But this is also a very different scenario than the grandparent example, where the cost of maintenance due to bad code quality is supposed to justify a ground-up rewrite. In the Flash example there is a clear business case for porting, even though it is understood the porting will expensive.
The fallacy is believing a ground-up rewrite will lead to more maintainable code. This is just developers deluding themselves. There is no reason to think a ground-up rewrite of existing working code will lead to better and more maintainable code.
As with almost every argument in this area that depends very much on context.
A substantial rewrite might be an opportunity to use better tools and improved techniques that have been developed since the original was written. In some cases that could represent a huge improvement in things we actually care about like developer productivity and the quality and performance of the product. Importantly this doesn't imply anything was done wrong or any bad decisions were made by the developers of the original product or the people who have maintained it so far. It's just that we work in a fast-moving industry and sometimes even a few years can see some big improvements in what the available technologies can do.
A development team starting with a relatively clean slate can take into account all the knowledge and feedback received over the lifetime of the existing system. Maybe it was too expensive to make use of those insights while evolving the original system but a new version can take advantage of them. Again that can represent big gains in areas that we care about.
It's often observed that a big rewrite risks losing a lot of small improvements and fixes that have accumulated over the lifetime of the existing system and of course that's true. However it's also true that a big rewrite can avoid a lot of existing design problems or get rid of long-standing bugs that no-one was ever going to get around to fixing.
I've seen big rewrites that didn't end well. But I've also seen big rewrites that were done for sensible reasons and had very positive outcomes. And I've also seen things that should have been rewritten but weren't and instead became a drag on everything. There is no universal rule here.
This is a hill I will die upon: The people who don't deserve rewrites ask for them, early and often. The people who deserve a rewrite rarely mention them, and in fact they likely already have done it, bit by bit as a sibling comment mentioned by way of example. I will say that I've often surprised myself with features I never would have hoped for on the refactoring road. Things that would have been entire Epics become six weeks of work, sometimes less.
Refactoring is the Ship of Theseus scenario. You replace the ship bit by bit, until it's both a new ship and the same ship. Yes, it's a titanic pain in the ass, but it's also atonement for your past bad decisions. Which are heavily populated with cut corners you will be able to spot the next time.
All worthwhile learning is effortful, and greenfield is the lowest effort path to anything. You don't learn much from greenfield except why greenfield is not a panacea.
That depends entirely on the reasons why they ask for a rewrite.
"I like this tech better", "I don't want to work with this tech", "This new tech is shinier": I agree with you, those are not solid engineering reasons.
"This doesn't interface well with the rest of the system because...", "This is going to cost us in the future because, ...", "This won't scale well because..."; I strongly disagree.
You may notice that the operative difference here is the term "because". If someone can give a quantifieable, technical, verifieable reason for a rebuild, then management should at least hear the guy out. They can still say no. But then the engineer did his job, and if the whole show goes haywire later because the 14 year old Java backend fails to scale up and the company loses money over that, nobody can say he didn't warn them.
The calculus of a project that has been running for 10-20 years is often different.
I've explained why - and why in some cases the approach you advocate is literally impossible - in my other comments in this discussion, which I invite you to read if you haven't already.
Can you give an example? I have a hard time imagining what kind of techniques cannot be applied to an existing code base with some adaption, but require the code to be written from scratch.
Another is when your platform evolves and forces the issue like the web plugins being replaced by new web standards that we were talking about before. Here you might not need to rewrite your entire application but you probably are forced to rewrite the affected parts and possibly significantly change the software architecture around them. A related example is if you previously wrote your application targeting a specific environment and now want to support multiple environments but the operating systems or frameworks or other dependencies follow very different conventions that impose some constraints on your software design.
