While I like the "start small and expand" strategy better than the "big project upfront", this trades project size for project length and often that is no better:

- It gives outside leadership types many more opportunities to add requirements later. This is nice is they are things missed in the original design, but it can also lead to massive scope creep.

- A big enough project that gets done the "start small and expand" way can easily grow into a decade-plus project. For an extreme example, see the multi-decade project by the Indian rail company to gradually replace all its railways to standard gauge. It works fine if you have the organisational backing for a long duration, but the constant knowledge leaks from people leaving, retiring, getting promoted, etc can be a real problem for a project like that. Especially in fields where the knowledge is the product, like in software.

- Not every project can feasibly start small.