There are many kinds of web development. Each is a stack of web technologies on the front end and back end that work together to create a web application. Some stacks have qualities the others don't and are good for certain uses, and not as good for others. It is like breakfast...kinda. As with any flat breakfast food, waffles, pancakes, crepes, and french toast all get the job of feeding you done, but in different ways. Web stacks are the same way. They all aim to do the same thing in different ways. Each has strengths and weaknesses that make them good and bad, but they all have a different paradigm. This causes most developers to fight for their favorite, but they all have their merits and uses.
A truly smart developer will take more of an anthropological stand and explore the ones that interest them and be careful not to start flame wars with the other groups who disagree. There is a lot to learn from anyone in the development industry, so listening and gathering data on all kinds of technologies is beneficial and recommended. Fighting over which dev stack is "the best" is like trying to convince someone to like waffles who only likes crepes. It isn't likely to happen. The rule of thumb here is "you like what you like" and be gracious enough to learn what you can from the other stacks whether or not you ever use them. You never know when your next job or side project will require the use of a stack you don't use.
Developers of different web stacks will often argue the merits of their favorite stack, to the detriment of the others. This is particularly prevalent among less experienced developers, who think the universe spins on how right they are. The truth is that no stack reigns supreme except in your own opinion.
Linux, Apache, MySql, PHP
Python, Django or Flask or Pyramid, PostGreSQL, etc.
Mongo DB, Express, Angular, and Node
Java, Jersey, Spring, Grails, Cassandra, etc.
ASP.NET, MS SQL Server, C#, etc.
Ruby on Rails Stack
Ruby, Rails, PostGreSQL, Unicorn, Rbenv, etc.