The thing to consider is that most of the files are tiny and have a few lines of code. It is suggested to link such files to the HTML.
For some external scripts, all DOM elements need to be loaded first, and it is therefore recommended to place the script-src call at the bottom.
This is extremely advantageous as it can save the web browser round trips to the server. This is because it no longer requires an external file to download from the server-side.
Consequences of Inline J.S.
Inline scripts are often seen in places such as Google Analytics tracking code, site verification, and introducing and setting proprietary and external scripting criteria for Webmaster Tools.
While these installations are fairly flawless, they can be difficult to maintain over time if they involve multiple pages. This is especially difficult when the code is passed by multiple developers.
With the possibility of code disputes and an integrated approach to things, a large decentralization can evolve into a larger one.