mmcc

In the first 5 or so All-Irelands the county club champions
represented the county. Then in 1892 the GAA allowed the county
champions to select players from outside the club when they got to the
inter-county stage. It was up to the club if they wanted to select
other players or not and some clubs continued to represent the whole
county on their own all the way up until the 1920's.
At that point most counties realised it made more sense to pick the
strongest selection from the best players in the county.

The remnants of that still linger to some degree today in many
counties where the captain of the county team is often a player who
plays with the club that is county champion and in some coutnies the
county champions get to name one or two of the team selectors also.

Another interesting fact is that the first All-Irelands in both
hurling and football were on an "open-draw" basis, there was no
provincial championship.
The irony is that, despite this fact, any move these days to remove
the provincial chps is usually meet with great reistance from
"traditionalists", even though their removal would make for a more
balanced "open" championship in both codes.