Large companies often have business people that drive tech initiatives. Once they come into a position where they need to propose goals, they will either need to lean on existing technical leaders in the org or reach out to firms that can technically scope their aspirations. Sometimes they might have just one year to prove their direction, so they aren’t going to wait around to develop in-house or hire for months and months trying to find a culture fit. They are going to staff in a hurry and get rolling yesterday.
Stay close to agencies that have leads at organizations like this because that’s a great way to get hired at a place you’d never expect to be working for (some random Fortune 500 company), and these hiring sprees don’t show up on LinkedIn or job boards. They go straight to the consultancies or agencies (you know, those pesky recruiters you never cared for).