Difference between metatable usage with newproxy and tables?

newproxy

I was looking up newproxy on the RobloxWiki and I noticed it creates a new userdata.

Now, my question is, what is the point of attaching specific meta-methods such as __index and __call, etc when you can attach it to a table aswell with the same functionality?

Why would you use a metatable with userdata values with new proxy instead of just using an array?

Why

local proxyValue = newproxy(true)
getmetatable(proxyValue).__index = {seraplz= function() print("@sera plz") end}
proxyValue.seraplz()

Vs

local meta = {
	__index = {seraplz = "@sera plz"}
}
local array = setmetatable({},meta)
print(array.seraplz)

Other than the obviously shorter way of doing the meta-table.

What are some strong advantages and disadvantages for both?