You are misunderstanding what "egalitarian" means.
I'm pretty sure that pifflesnort got it correct. Egalitarian means that people are equal and deserve equal rights and opportunities. But open source communities do not treat people equally. If you've never learned to write a good bug report, you're marginalized. If you've learned to program and have time to contribute, you're likely to be able to have a significant impact on the project that you're interested in.
It is true that the economic barriers to entry are fairly low. I've personally known multiple homeless people who found open source to be their gateway to learning a useful skill and getting a good job. (Most who know the ones that I am thinking of do not know this detail of their lives...) But there are other types of barriers to entry. Language skills, intelligence, interest, etc.
It is easy to ignore those requirements. But stop and think about the fact that significantly less than half of adults in the USA can read, write, and do math at a grade 8 level. A lot of the reasons why have to do with unequal opportunities (bad schools, families that discount learning, etc). The fact that open source communities ignore those people rather than actively seeking to give them access is a demonstration that open source is a meritocracy, not an egalitarian society.
Egalitarianism and meritocracy are not mutually exclusive nor orthogonal. A dyed-in-the-wool egalitarian in need of advice on wood will still seek a carpenter over a weaver.
What is a 'starting point'? Open source certainly doesn't provide equal starting points, because each individual is evaluated on merit, the acquisition of which is often tied to social and economic background.
Conferences don't provide equal starting points, for the same reason.
> Egalitarianism and meritocracy are not mutually exclusive nor orthogonal.
They are orthogonal. An egalitarian meritocratic society would give each member equal opportunity to achieve, but would judge the achievements of each member according to their merit.
Open source only concerns itself (like any sane organization whose mission is not social advancement) with merit, not with egalitarian questions of how merit was acquired.