It probably has to do with psychology more than anything. My mental model of this sort of development (if you'll permit me to be a bit florid) is of an eternal pilgrimage of small incremental improvements, without any fixed destination or many real landmarks along the way. The TODO list for mitmproxy has never grown shorter (and never will), so I just never reached a point where declaring a 1.0 was obviously right. I realise this is eccentric, doesn't reflect the maturity of the project, and is probably not the way my co-maintainers think about this, hence the change.

For much the same reason, I'd like to de-emphasise major version increments as flag-fall events. Incrementing the major version inline with our development cadence makes sense from that perspective.