Same here, I just hate PayPal documentation, and the way they managed to keep it shitty over the years.
Braintree (A division of PayPal) has nice documentation though.
Looks like Magento2 could make use of this, every part of it is too over-engineered, adding un-necessary complexity to make it look like enterprise ready application
A lot of things happened in php world,since you last checked, which is apparently ~ 5 years back. for starters go read about Magento 2 codebase and its code organization and deployment strategy. Whether you do FTP based file deployment or sophisticated CI/CD build, it all depends on developer not programming language you are using.