Do you want to deploy an e-commerce site on a budget and then leave it to get hacked and pwned because your client is a total dipshit "brand manager" who doesn't understand the security implications of running a ridiculously popular, hella exploitable open source e-commerce solution?
Congratulations, you sick fuck, because that's the only thing Magento is good for.
Have you ever noticed that the Magento logo looks kinda like a hanging dong? That's appropriate, because once you start working on a Magento site you're getting fucked, every day, until you finally rage quit.
But it's extensible!
Yes, yes it is. If you really want to reach your hand into gaping anus that is Magento and start fucking around with the internals, you certainly can. But you will never be able to unsee the horrors that lie before you. You'll think back to reading this as you attempt to unravel 10+ levels of inheritance so that you can figure out why a minor release broke your extension, and you'll realize you might as well be reading a map of hell written in backwards latin.
Do you think it's fucking cool to work on a piece of software that actively hides error messages while also failing to log them in any useful way? Do you wish your life involved more dependency hell and conflicts? Have you ever wished you could program in pure, shitty XML?
How bad can it really be? It uses composer! It's been rewritten!
Sure, it uses composer. It uses it wrong. Running composer install will modify files in and out of your vendor directory, because fuck you. Secondly, yes - it's been rewritten. If you think it's praise worthy that Magento 2.0 finally started using real OOP with namespaces and interfaces and shit, you're far too fucking stupid to be outside of a padded room.