The reasons provided - actually, one reason - is that whenever you need another feature (the second reason provided is the ability to run on another platform) it's easier to just use whatever is there already in the existing software rather than making that feature yourself.
This is a pretty general problem of writing your own parts or taking external pieces, often called "dependencies".
There are problems (and benefits) with those external pieces, not mentioned in the article - cost of learning (vs. cost of creating), cost of bugs (you usually know bugs in your code better), ability to fix bugs (sometimes external teams take forever to do that...), weight of features which you don't need but which exist anyway in the external software (that code takes space, time and sometimes require you to work with that a certain way when you'd maybe prefer another)...
I fully agree that educational value of creating such a system from scratch is quite significant though.
The reasons provided - actually, one reason - is that whenever you need another feature (the second reason provided is the ability to run on another platform) it's easier to just use whatever is there already in the existing software rather than making that feature yourself.
This is a pretty general problem of writing your own parts or taking external pieces, often called "dependencies".
There are problems (and benefits) with those external pieces, not mentioned in the article - cost of learning (vs. cost of creating), cost of bugs (you usually know bugs in your code better), ability to fix bugs (sometimes external teams take forever to do that...), weight of features which you don't need but which exist anyway in the external software (that code takes space, time and sometimes require you to work with that a certain way when you'd maybe prefer another)...
I fully agree that educational value of creating such a system from scratch is quite significant though.