the supply is rising if the price is falling and vice versa? - it does not make sense
the supply should be rising when the price is rising and vice versa.
maybe this stuff is traders business but from an economics point of view this does not make sense at all
When the price is going up people tend to pull their ask in anticipation of a better price to sell at. When the price is dropping people tend to pull their bids in anticipation of a lower price to buy at. At the same time in a falling market a lot of people wants to sell and places sell walls hoping to get out at a better price, and vice-versa.
Also, if someone is in the process of accumulation, he often masks his intention with having the bought coins in asks, trying to cap the price. Similarly a seller would use bid walls to try to keep price higher while he is unloading. I have tried these techniques in a liquid market (Bitstamp BTC/USD) and in a short term (a few hours) and medium trade size (100-200 BTC), they lead to an average 0.45% better execution than not employing them. That is only possible for medium+ traders who have the required funds to put up walls, and only for medium- trade sizes, because large trades affect the market nevertheless and the strategy becomes evident to an observer, if there is simultaneous buy pressure and sell walls. It may be +EV still, though, as I see it being used in Bitstamp often now.
Then there is the "legitimate" use of walls in illiquid markets. Offering a trade at a favorable price near market (lower or even higher) for a large counterparty. Buying at market would lead to slippage.
The depth that is reasonably far from the market to not be fulfilled except in extreme cases is safe to discard from analysis. Every trader would buy XMR at 300 or sell it at 500, it does not matter how many stated intentions there are listed, if you want to know where the price is heading.