A lot of symbols can be accessed with Alt Gr compared to Windows
- you can’t make a ?.. or !.. with it
- the spacing between the dots is awful in a lot of fonts
- it is hideous in monospace
- typing ellipsis properly is a very easy gesture (triple-tap the dot key), arguably easier than Alt Gr + . (depending on the keyboard)
But an ellipsis is separate from and doesn't mmerge with sentence-terminal punctuation, whether its a period or somethig else (when it replaces words at the end of a sentence, the terminal punctuation follows the ellipsis, when at the beginning of a sentence that follows another, the ellipsis follows the punctuation.) The constructs you say can't be formed with it aren't needed.
Meanwhile there are a lot of languages and cultures. Somewhere all those characters were useful for something. My Atari had a very fun utility that gave you a compose-key that could combine just about everything on the keyboard to access all those weird characters of the extended ascii table. <compose>+ao would give you "a" with a ring on top (å), <compose>+ae gave the danish welded together character that I can't even type any more on windows.
The idea came from some unix thing I believe.
Compose ` e produces è
" a produces ä
v s produces š
v S produces Š
a e produces æ
C = produces €
l - produces £
- > produces →
( 1 ) produces ①
^ 1 produces ¹
_ 1 produces ₁
1 8 produces ⅛
- - - produces —
- - . produces –
. . produces …
. - produces ·
| - produces †
| = produces ‡
" < produces “
x x produces ×
m u produces µ
> = produces ≥
I have also configured Shift+Compose to send the code 'dead_greek' using ~/.Xmodmap:
keycode 135 = Multi_key dead_greek Multi_key Multi_key