I like to joke that 90% of my job is just telling developers “No you can’t rewrite that.” Joel Spolsky explains why, and why why you’re not reading this in a Netscape browser, in his seminal article Things You Should Never Do, Part I

When you throw away code and start from scratch, you are throwing away all that knowledge. All those collected bug fixes. Years of programming work.

You are throwing away your market leadership. You are giving a gift of two or three years to your competitors, and believe me, that is a long time in software years.

You are putting yourself in an extremely dangerous position where you will be shipping an old version of the code for several years, completely unable to make any strategic changes or react to new features that the market demands, because you don’t have shippable code. You might as well just close for business for the duration.

You are wasting an outlandish amount of money writing code that already exists.

Which is why this parody template of a press release had me in stitches – Why we at $FAMOUS_COMPANY Switched to $HYPED_TECHNOLOGY

When $FAMOUS_COMPANY launched in 2010, it ran on a single server in $TECHBRO_FOUNDER’s garage…Our existing technology stack has served us well for all these years, but as we seek to grow further it’s clear that a complete rewrite of our application is something which will somehow prevent us from losing two billion dollars a year on customer acquisition.

…the $FAMOUS_COMPANY backend has historically been developed in $UNREMARKABLE_LANGUAGE and architected on top of $PRACTICAL_OPEN_SOURCE_FRAMEWORK. To suit our unique needs, we designed and open-sourced $AN_ENGINEER_TOOK_A_MYTHOLOGY_CLASS, a highly-available, just-in-time compiler for $UNREMARKABLE_LANGUAGE.

Read the whole thing, as they say.

Legacy == Proven. It’s as true today as it was when Netscape was on top and threw it all away.