Any time any part of the hand touches the bass the one thing we cannot see is the pressure used. We cannot see or hear pressure so it is a hard quantify how much is being used.....if any at all.
In my techniques, especially pick use, it is there because of the design of the hand (the little finger is on the far right of my hand and so is the bridge) so the will meet at some point, but because i am holding a pick, most of my fingers are occupied with that task.
If i play certain lines, then yes my little finger will take a little more pressure from the hand if the lines i have to play are a more precise (little muscles taking over from big muscles). When i use a pick up by the neck, again my little finger will get involved, but that us because in all my pick use i do not have any onther finger free to do it, and again the little fibger is on the far right of my hand which this time is next to the strings and body...so hand ergonomics makes it easy to use.
In finger playing it may rest on the strings, but if i am playing up by the bridge it may look like i am resting on it, but there is no pressure...it is just an illusion of the technique.
But again, it is about using the minimal pressure and the correct technique, applied by the best muscle groups to handle the task.
The little finger was not designed for support, so if the big muscles on its line (upper back, shoulder, upper arm, forearm) push down to hard it will get damaged over time, add in any extra influence of the elbow and it could be serious instant damage you notice right away.
Look at it this way, a tree has a big trunk and gets smaller the further it gets from the ground, the branches are bigger next to the trunk, but never bigger or as thick. As the branches get further from the trunk they to get smaller, again everything as it gets further from the ground/trunk gets smaller, and it does when it gets further from the trunk.
We are similar, our body has a central trunk and everything the comes from it gets smaller the further away it becomes from it....if not... the the weight of the the appendages would be weak at the point of attachment and snap just under the pressure theie own weight would create.
We can relate weight to pressure, so to much pressure on the little finger (or any finger) will damage it.
LIke i said, try and learn to use minimal forces and pressure on the bass, it feels funny doing it, but it can be learned.