> I'm trying hard to figure out why someone want to use something like this or React There are many reason why one would want to use framework X,Y,Z instead of

> I'm trying hard to figure out why someone want to use something like this or React There are many reason why one would want to use framework X,Y,Z instead of writing his own (because at the end of the day, any large application will need some form of framework/toolkit to be maintainable). The first reason I guess is that in practice the code you depend on is the code you don't have to maintain and test. The second reason is politics. You work with 50 engineers. You decide to write your own toolkit. I'm pretty sure you'll end up having endless debates about what is the right architecture. Now if you tell the rest of your team or the management "Facebook/Google is using that, they can't be wrong", It can save a lot of time. The third reason is "laziness". Many "engineers" using React or AngularJS actually don't know how the DOM really work, like many people only know jQuery and not standard DOM API in order to perform a task, or many "engineers" don't know how to write CSS so they use Bootstrap. Yet the same engineers are writing 1 million dollars SPA for Fortune 500 companies ... Frameworks are a trade-off. By learning one, you expect the investment to save you time, maintenance cost and not to be leaky(i.e. not having to understand the internals of a framework in order to use it). In an era where engineers are asked to be backend engineers, front end engineers, DBA, UX/UI specialist,data analysts, statisticians, server administrators, to know the OSI model from top to bottom,to know 10 languages with 5 years of professional experience in each of them and what not, some engineers don't consider learning the fundamentals of the DOM a worthy investment.