I agree on this request.
We'd go a step further and suggest it should be a portfolio level setting. Our use case is that in some portfolios projects should only be created by:
- Fusion (via integration from a 3rd party system)
- Using a Request (where Fusion does the conversion)
The "new project" feels like the right place to click for users who have forgotten training or have "chosen" to teach themselves. This just creates projects that have to be manually cleaned and created through the correct path.