Let's use an example:
The character Character is built on 200 base points plus 150 points in disadvantages. Character wants a follower, aptly named Follower, also built on 200 base points plus 150 points in disadvantages. Follower costs 40 points (200/5), so Character pays 40 points. Now Character's base point total, not including the follower Follower (like you said), is only 160 points. Follower now, instead of costing 40 points, costs 72 points ((160/5) + (40/1)). Wait, now Character's base point total, not including the follower Follower, is only 138 points. Follower now, instead of costing 40 or 72 points, costs 100 points ((138/5) + (72/1)). But wait, there's more. Now Character's base point total, not including the follower Follower, is only 100 points. Follower now, instead of costing 40, 72, or 100 points, costs 120 points ((100/5) + (100/1)). Uh-oh, now Character's base point total, not including the follower Follower, is only 80 points. Follower now, instead of costing 40, 72, 100, or 120 points, costs 136 points ((80/5) + (120/1)). Oh no, now Character's base point total, not including the follower Follower, is only 64 points. Follower now, instead of costing 40, 72, 100, 120, or even 136 points, costs 136 points ((64/5) + (146/1))...
Do you see why I might have thought you were wrong about that point?
-Preston