I've found that it's mostly about trade-offs.
The trade off to this is how readable is the code to 90% of people writing and maintaining php and is having the readability knock worth the 0.00005 second saving?
if this is in reference to FP, then remember they're just another function like
substr, granted they've been written to be far more flexible and extensible than a average function; but doesn't immediately imply unreadability. Remember the first time any language was created, it's syntax would have been foreign, similarly when new features were introduced like covariance and contravariance, just because you didn't know it, doesn't mean the rest of the team shouldn't use it, or have to litter their code with training wheels (the stuff you should find in function reference).
You should have also seen that the inners workings of the flatmap example I shared is not something foreign: it has foreach loops, null checks, and a call back function -- all common elements in code.
Most of all, Comment Your Code (something I don't do often enough) so the person coming after you (usually you in 3 years) knows what you were thinking, planning and doing. In that 3 years your method of thinking is probably going to have changed and you're going to be wondering why you did something in a certain way - leave clues behind so you can remeber why.
Agreed, but the level of commenting shouldn't overstep a language reference, but rather explain difficult or compex techniques; but again as with anything, within reason.
Personally I prefer code comments to follow a standard; a good approach is always to write (htmldoc) documentation comments as these can then be turned into html documentation (htmldocs). Almost every language has a facility for this, with PHP it's e.g.
https://www.phpdoc.org.
Excessive comments in code is only a source of frustration when you fail to keep it updated, and yes that implies every programmer working with the codebase. There is nothing more frustrating than finding stale comments that don't reflect the changes.
That said the amount or proliferation of internal comments (not htmldocs) is always going to be more when you're starting out or trying to deal with the unfamiliar.