There are no two ways about it, learning-by-doing is the most effective way to retain what you learn. Having said that, training on machines, while useful, often requires teaching outside normal hours of a machine’s operation or using a dedicated offline machine. Both options are scarce and expensive.
This resource bottleneck convinced many hardware companies to explore alternatives that scale their training efforts, while reducing costs. Even before any of us knew what “social distancing” was, many companies were already starting to blend in-person and online training. In parallel, the WFH (Work from Home) trend was rising fast. So the gradual migration to more online training was already happening.