Installing Xcode 7.x on El Capitan 10.11

I am on an old MacBook (mid-2009) that is not supporting Sierra. When I go to the App store to install Xcode 8 (only option available) it says that it is for 10.12 (Sierra) only. That means that if someone has El Capitan only and didn't install Xcode 7 before, cannot start developing apps for macOS / iOS? That seems absurd to me, El Capitan is still a modern OS... I might understand if you are on Leopard, but El Capitan is from 2015!

Is there any way to (legally) bypass this problem?

The last Xcode version compatible with El Capitan is Xcode 8.2.1. If you can't install it from within Apple App Store, visit Apple Developer and download the app there. An Apple ID is required.

Xcode is provided as xip file (signed zip). You can simply unzip it by using Archives.app (i.e. with a double-click).