I will not, beginners who want to build a web app should start with JS. Until Python is executed client-side as quickly as JS, "fullstack python" is a lie.

I think, in this context, "beginners" refers to new Python programmers who want to use Python to build a web app.

After all, the site's intro clearly states, "You're knee deep in learning the Python programming language...Now you want to take your initial Python knowledge and make something real. A real web application that's available on the web"

I started with Flask because I knew some Python. I just moved to node.js / Meteor. I wish I had started with the latter. I wish someone had told me "Python is nice, I understand that you're enjoying it right now, but learn these JS web frameworks." Anything else is a real disservice to beginners.

Said no one ever.

This is just plain wrong to force someone with your new hype and vague idea of how a web application should be developed using only your new hipster framework of choice and nothing else.

There are tons of way you can write a web application, that's why open source is cool, chose the one that pleases you and have fun with it, but stop trying to prevent others using anything else but what you judge to be the best.

I'm the complete opposite you are entitled to your own opinion but I started with node.js / Meteor, I moved to Flask, and learned Python, and I've never looked back.

I have strong opinion (you might disagree with me) that Javascript should stay in the browser, like it was designed for, and inherited to browsers to this very day.

Javascript is not a beginner-friendly language, though lots of beginners manage to create things with it. It has quite a few rough edges and teaching Javascript can be rather annoying.

When a single PC circa 2014 is more powerful than the entire world's combined computing power circa 1990, and a smartphone is as powerful as an XBox, it's probably suboptimal to worry about execution performance. Generally, it's best to wait until a profiler indicates there's a performance problem before changing your coding habits.

Is my phone battery an acceptable profiler?

It doesn't warn me about performance issues, but it lasts less when I visit heavy websites.