Every day the inactive players are wiped from the servers and they leave anchors behind open for founding too, therefore a few lucky players can found on farming islands... what makes me think on long term this change without adjustments might trigger creativity how to increase the number of those anchors.
You could maybe open farms on rocks too, at least 3 would fit on all of them
or screw the farms and make the rocks special... add farmable camps, so more players would want to populate them and found early, who could reject extra camps?
or to develop the original idea: whenever an island is filled with beginners, a neighbor island will open and then a 2nd island...., what if you would offer on the first neighbor island anchors with possibility for invites and founding and only let the random new players join on the 2nd island? This would help to stay in cluster, but give a healthy distance for beginners too later on, who join a few months late for example.
Late game: it is good to have higher population without losing the chance of CS capability.
I consider keeping level 10 harbor in flyer cities from now on. Normally I demolish every building, but it only costs 40 population that's not a big sacrifice.
Most of the time I only lose the land units and spare my transports and naval escort in defense cities, therefore the barrack works on overtime and the +10 extra harbor levels were luxury for flexibility and to be CS capable in all cities. If I lost the 80-100 bireme escort in support cities, the rebuilding time of a level 10 harbor isn't much longer (about +19%) compared to level 20, you can compensate it easily with spells, tokens, researches.
On a 100 city scale these logical changes could probably spare almost an extra city worth population for conquest players like me, without affecting rebuilding time. That's bigger change than I thought, I like it more now.