Bash Function/Alias name collision causes seg fault

The problem in this post also happened to me.
mkdir crashes bash

I couldn’t comment there because no reputation.
Can anyone elucidate why this happens? It happens at runtime Not when the function is loaded.
Here is the paste of the identical issue.

md() 
{  
    [ $# -eq 0 ] && { echo "$0 dirname [permissions]"; return; }
    [ -d "$1" ] && { echo "%1 already exists!"; return; }
    mkdir -m ${2:-0755} -p "$1"
}

"Problem was that I had previously had an alias like alias md="mkdir" so when bash parsed the new bash function, it expanded the md() to mkdir() and the function became infinitely recursive and crashed the shell. "

I felt this issue was aptly found but i do not understand the reasoning.
I don’t understand any possible reason the alias expansion is misdirecting the fully qualified shell function. Backwards right?

Sorry for the dupe, please read why before a callout.

>Solution :

"Aliases are really just text replacement macros – so when you try to define md() { ... } after defining md=mkdir you actually end up with mkdir() { ... }. Try printing out the function defs with declare -p -f md and declare -p -f mkdir to see what I mean." – steeldriver

zi@zi-top:~$ declare -p -f nd
bash: declare: nd: not found
zi@zi-top:~$ declare -p -f mkdir
mkdir () 
{ 
    mkdir -p "$@"
}
zi@zi-top:~$ nd () {
        mkdir -p "$@"
}
zi@zi-top:~$ declare -p -f nd
bash: declare: nd: not found

I see that what steeldriver said is true, i think it`s a strange architectural decision with prob some kind of reasoning in the code is text bashism wurl.
Thanks!