Step 1 - You do it all server-side, and some people start requesting interactivity. Step 2 - You push a few client-side templates as data, so you can do intera

Step 1 - You do it all server-side, and some people start requesting interactivity. Step 2 - You push a few client-side templates as data, so you can do interactivity. Step 3 - Your server side framework (not surprisingly) has no support for client-side templates, so you add hack over hack to get the more and more complex you need here and there. Step 4 - You move those few components into a client-side framework, and interact with them through hacks that your server-side framework doesn't support. Step 5 - Hell, why insist on using 2 entire GUI frameworks? You move all components into the client-side one and ditch the hacks! Step 6 (bicycle on the floor and you hurt) - Your server-side framework doesn't interact well with the client-side one, so you move into JS everywhere. This progression still seems unavoidable, but the web standards evolved almost as much that there's a light visible at the end of the tunnel.