Excellent writeup and good advise for newbies.
One thing I would like to add: the mistake of not keeping things simple.
Using React or any other JS framework for a simple website may be too much.
Using a huge icon library to display three icons may be too much.
Using a huge CSS framework for 5 elements and some basic layout may be too much.
Yet people build huge stacks and add so much bloat to the simplest websites.
If you can reduce the number of dependencies, whatever they are, do it.
If you can reduce the number of elements/modules on your site without striping off important information, do it.
Keep things simple wherever you can and where it makes sense, because things are just complicated and complex enough.
For a junior building a portfolio project for example, I wouldn't worry about too much using tools that are an overkill. Many of my personal projects use React or Vue even if they could be simple static sites with vanilla JS. Why? Because it allows me to experiment and learn since my side projects rarely grow big enough to warrant the use of these tools.
In "real life" apps, I totally agree.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.