Donald Knuth was 40 years old when he published the first version of TeX.
We could make a long list like this. Enormous amounts of high-quality, game-changing software is written by coders in their 40s and 50s, often with a couple more decades of stewardship and expansion of their works.
Isn't unique to programming either. Loads of famous people produced something well known today in their later years. Many of which didn't start picking up the required skills before their late 20s, 30s, etc. Many works which in many ways, were far more difficult than programming is today.
It's primarily navigating social environments which makes software production so obscenely difficult. There's nothing inherently complex about most popular web apps once you have access to the frameworks used to make the tough parts easier. No amount of frameworks or technical knowledge is going to solve stakeholders with conflicting interests, or coworkers heavily in favor of slowing things down through unnecessary red tape.
We could make a long list like this. Enormous amounts of high-quality, game-changing software is written by coders in their 40s and 50s, often with a couple more decades of stewardship and expansion of their works.