Three things. The volumes are small, the buying decision involves several people with different questions, and the gap between the first search and the signed contract is measured in months. Each of those breaks a habit that works fine in consumer SEO.
Small volumes mean keyword research by volume is actively misleading. A term searched 120 times a month by operations directors at mid-sized manufacturers is worth more than one searched 12,000 times by students and jobseekers. The reporting dashboard cannot tell the difference, which is why so much B2B SEO reports growth while the sales team sees nothing.
Buying committees mean one page cannot do the job. The person who finds you is rarely the person who signs. You need the practitioner page that answers how it works, and the page that answers what it costs and what it replaces, because the second one is what gets forwarded upward.
Long cycles mean attribution is hard and patience is required. Someone reads a comparison page in March and fills in a form in July having searched your brand directly. If you judge SEO on last-click attribution in a six-month cycle, you will conclude it does not work and switch it off just as it starts to.