I suppose it could be considered steep for anyone making a multiplayer game while managing the hosting for themselves on a tight budget. Developers with strong knowledge of monetisation strategies can make good revenue streams from games with self-hosted or self-managed servers. Maybe these developers wouldn't be able to get the same amount of revenue if they used Roblox instead.

What Roblox provides is a platform to upload experiences to with minimal risk or skill required, and services that are heavily subsidised by money redirected from their most successful experiences. The barrier to entry is lowered to the floor, and most kids using the platform to learn game development wouldn't have otherwise learned about it if they had to manage servers, study networking, etc.

Cloud services are a thing, but they're usually expensive and Roblox is paying for them for you. Free cloud services are a thing, but they're usually very limited and what Roblox is providing is essentially unlimited.

For me, the killer app for Roblox is none of this. It's Creator Rewards <https://create.roblox.com/docs/creator-rewards> (previously Engagement-based Payouts (previously Premium Payouts)), a programme where any player that pays for a Roblox Premium subscription (or is a new/returning user and buys anything on Roblox in the future) results in money earned for the developers of the experiences they play. This happens without requiring any monetisation strategy, microtransactions, or paid in-game products to be created by the developer. Nothing similar is provided by most other popular game engines or platforms.

For myself as a smaller Roblox creator with no interest in creating such monetisation strategies on my own experiences, Creator Rewards makes up a much bigger income proportion than it does for most large developers on the platform. Instead of ~10%, it's more like 90% for me, and I suspect that most kids learning to code games on Roblox without having good marketing skills are in the same bucket, and so the cut won't be nearly as steep for them.