Can someone explain this weird font behavior? (EBGaramond-Maths)

I am using the package EBGaramond-Maths.

This font is missing the symbols for these commands (from documentation):

\leftharpoonup \triangleright \flat \smile
\leftharpoondown \triangleleft \natural \frown
\rightharpoonup \star \sharp \vec
\rightharpoondown \partial \t

The default way of loading this package (as per the documentation) is

 \usepackage[cmintegrals,cmbraces]{newtxmath}
 \usepackage{ebgaramond-maths}

When the above-mentioned missing symbols are used, the package prints nothing out at the command, which is to be expected. However, if we use only newtxmath without the ebgaramond-maths package, the symbols are correctly produced. Thus, we can surmise that newtxmath has those symbols, but ebgaramond-maths does not.

However, this would suggest that when ebgaramond-maths is loaded, the compiler essentially "blanks out" the positions in the character map that the ebgaramond-maths lacks, rather than falling back on a previously loaded symbol. For example, although the \partial symbol is loaded by the newtxmath package and displays correctly when it is used without ebgaramond-maths, after loading ebgaramond-maths thereafter, the command does nothing.

1) Why does this happen?

2) If ebgaramond-maths just cancels whatever newtxmath does, then what is the point of loading newtxmath before?