Normally a startup is innovating in one vertical, disrupting the market with new ideas or technology which enables users and the company itself to profit of those innovations. This continues normally until the startup has become number one in that vertical. Then it must defend its spot against other newcomers who want to disrupt. Part of the defence is diversification, use the capital to disrupt in other places as well. This has been the natural progression of every successful business I know. At some point that company is so big though, competing in so many verticals that it becomes stale. It stops innovating and is constantly on the defence. Only innovation comes through acquisition which is often just a way to defend your spot by buying early.
GitLab is sort of not even trying to become number one in one vertical. Like the CEO said in his interview, GitLab already competes in 9 different verticals (JIRA, Jenkins, GitHub, NewRelic, Artifactory, etc.) and they are not near the top anywhere yet. They are going to become stale before even reaching a single peak in any industry. So far they have not innovated anything yet. Their only innovation is "free private repos" and "cramming 9 different domains into one product", which is nothing more than a pricing strategy and a lack of focus and not an innovation. It's painful to watch. Their business model looks like their products: an absolute mess.