What is Upwork's persistent economic moat as marketplaces evolve: scale of talent, SaaS, or something else?

First, of course, is the marketplace liquidity and selection: the fact that a marketplace can get transactions done, because they are attracting supply, that attracts demand, and that attracts more supply and so on. There are network effects here, because my selection choices as a business go up as more workers come onboard. On the worker side, my opportunity to find new work goes up with every new business that comes onboard. That’s hard to start, and once you reach a certain scale, hard to dislodge, witness Craigslist traffic still today. That's a big moat.

Another huge moat is the proprietary data that all these platforms are collecting about these different classes of work, whether it's about the performance of the client, or the contractor, how successful they've been, how they perform, there are all kinds of quality and differentiation signals. User behaviors allow platforms to create a quality score, and there's an immense amount of data that's being collected about the contractors. Similarly, to a lesser extent, you're collecting data on the client side about how responsive they are, how fast they do things, how many times they have disputes. The data that's being collected ultimately helps, it gets fed back into the system, it makes it easier to do the matching and hiring, and it increases the chances of job success - ultimately it helps with the outcome the client is seeking. 

Related is that proprietary data also enables AI/ML across every stage of the hiring process. When you're starting out, you have no data and so you have no AI, and you have no optimized matching, whereas at scale, all these things kick in. These two things are the way I look at it.