There seems to be a myth being put around that CSS Grid Layout is going to be really difficult to learn, so difficult that poor web developers will never use it. I call nonsense. I have seen the stuff people learn on a regular basis. The average framework has a grid system more complicated to understand than Grid, you don’t have to get far into Sass to be dealing with concepts far more difficult than those you get in Grid.
I also don’t think web designers and developers are stupid and incapable of learning things, and I’m one of the few people who has actually taught grid in a classroom situation. When I do that, the comments I get from students is how straightforward grid is. I’m a decent teacher, but I don’t think that I could make something horrifically complex seem simple.
The other thing I have seen asked is why is CSS Grid Layout so complicated looking? That’s a more reasonable question, as the people making this statement generally haven’t been working with Grid yet. If you haven’t yet started solving real problems in production, it is very easy to wonder why all this stuff even exists. It may be that even if you have started working with Grid, the type of problems you need to solve never call for some of the more complex parts of the spec.
However, you not needing them is not the same as them not being necessary. The same is true for any specification or any bit of software. As a product owner I sometimes get customers wanting to know why there are a number of options to do a certain task, why have we made this more complex than it needs to be? This attitude usually comes from a place of not understanding that a piece of off the shelf software has to solve more than the needs of one individual.
If you were writing your own CMS, for the needs of the types of projects you work on, you could make a whole lot more assumptions and leave out far more stuff than we can with a CMS that 10s of 1000s of people install. So it is with a CSS specification, except we are talking millions of people, doing all kinds of things, along with any number of browsers and other user agents needing to deal with the websites those people are making with it.
So, you might not need all of it. You might not need any of it. The CSS Working Group aren’t about to burst into your office demanding that you put down your floats. However, you might be interested, or you might be running into problems that your existing methods don’t solve well. In that case, I’d suggest that you start simple and then ask some questions based on things you know you would like to build.