Why words with accented characters can't be automatic hyphenated with the default OT1 enconding?

I was reading the first answer to this question: Why should I use \usepackage[T1]{fontenc}?

[...] the default font encoding (OT1) of TeX is 7-bit and uses fonts that have 128 glyphs, and so do not include the accented characters as individual glyphs. So a letter ö is made by adding an accent to the existing 'o' glyph. This means, among other things, that words containing accented characters cannot be automatically hyphenated.

I can't see what is the relationship between the fact that a character like 'ö' has to be made from two different glyphs (the 'o' glyph and the accent glyph), and automatic hyphenation.

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On a side note, I wasn't sure if I should ask this in a comment on the answer itself. In the end, I decided to make a complete new question. –  Julian Lamas-Rodriguez Jul 31 '10 at 13:15

FAQ 1: "TeX’s algorithm for hyphenation gives up when it encounters an \accent command".

FAQ 2: "The candidates for hyphenation must be sequences of letters (or other single characters that TeX may be persuaded to think of as letters) — things such as TeX’s \accent primitive interrupt hyphenation."

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+1 Good answer. –  Will Robertson Aug 1 '10 at 14:17
This is a good argument in favour of using `\usepackage[utf8]{inputenc}` and then directly typing accented characters. This way, I believe, hyphenation can occur as expected... –  Seamus Jan 20 '11 at 17:00
@Seamus: I suspect that input encoding is irrelevant here. This is an argument for `\usepackage[T1]{fontenc}`; differences in input encoding disappear early on (tex.stackexchange.com/a/44699/1340), I believe too early for hyphenation, while font encoding makes a difference (tex.stackexchange.com/a/677/1340). –  Blaisorblade Mar 16 at 19:29
Blaisorblade wins - the T1 font enc allows me to add hyphenation in accented words: \hyphenation{thermo-\'electriques} thanks boys! Matthieu –  matthieu Jul 10 at 13:35