MBP is what most depth-of-market ladders display and what most traders actually need. It is cheaper to carry, simpler to maintain, and adequate for reading structure and imbalance.
What it cannot tell you is composition. Ten thousand shares at a price could be one committed order or forty flickering ones, and the trading implications are completely different.
Example: an MBP feed shows level 5,000.00 with 850 contracts. It drops to 600, then back to 900. You cannot tell whether 250 traded, 250 cancelled, or 250 cancelled and 300 arrived. MBO answers that unambiguously; MBP forces inference.
Related: market-by-order, depth-of-market, level-2, order-book-imbalance