Why is "distro", rather than "distri", short for "distribution" in Linux world?

My guess is that distro might have been inspired by shortenings like repo[sitory], algo[rithm], memo[randum] &c.

Due to the Latin influence, "-o" is a much more natural-sounding ending for a singular noun in English than "-i". My best guess is that this subconsciously affected the coinage.

The pronunciation of "distribution" is:

dis·tri·bu·tion — [dis-truh-byoo-shuhn] — /ˌdɪstrəˈbyuʃən/

"-stri" would typically be pronounced similar to the beginning of "street" or "stripe".

"-stro", on the other hand, would be pronounced similar to the beginning of "strobe" which isn't exactly the same but close enough in American English that we'd rather say "distro" than "distri".

Furthermore, the "-tri" ending is very rare in English with "-tro" being slightly more common.

If you create a new word, similarity to already existing words makes the difference between "sound good" and "sound weird".

"Distro" is very similar to already existing word "bistro". There are also "maestro", "electro", "nitro", "metro", "retro" etc.

On the other hand, I don't know any word with singular ending with "-tri". It looks like some plural form (like "uteri").