If I correctly understand what you are saying

You did not, but he also picked an example that could be conflated with the 4-spaces issue.

They're talking about situations where you might want to align text by a number of spaces that isn't divisible by your tab size. I'll expand on their example:

function test(&obj, &obj2, &a) {
$obj->doSomething()
....->doSomethingElse()

$obj2->doSomething()
.....->doSomethingElse()

$a->doSomething()
..->doSomethingElse()
}

Again, dots are "visible spaces" in this example, and being used to align chained methods with the length of the object name.

Correct. The way I'm used to it ( and how I thought the world worked ) is that the IDE gives tab a fixed length or characters. If you set it to 4 it would be the equivalent of 4 spaces or 4 letters or whatever.

If my tab is set to 4 it would take up the width of 4 characters. If I need two indentations I would press tab twice.

If bob then checks out my code and calls me a maniac and sociopath for using indentation and swears by "2", the code would just look more condensed. The alignment would still work out because that's done through spaces.

var user_name = "Bob"
var user_age[tab]= "Bob"

This would align the = for Bob, because it needs two characters to align and that's what his tab width is. It wouldn't align for me because my tab width is 4. So I would.pur two spaces instead of the . That way it is aligned for everybody regardless of their tab width settings.

The way you explain it sounds like how tabs works in MS Word ( or other word processors ).

I don't think I could work like that. I've only ever used IDEs to code ( regardless of how primitive they were back when I started). Interesting take though :D