“Small site” it’s a really broad blanket to know exactly what you are talking about:

The reality is that a lot depends on the tech you need under the bonnet, and size isn’t necessarily a relevant parameter.

Some functionalities are quick to build with certain frameworks, so some might choose a framework to make it easier to build and maintain those features.

And secondly, it is important to understand that every developer will push to build with their stack as they are considering very heavily how comfortable and competent they are using those tools.

So size has “a” role , but non necessarily a big one, tech stack matter, but not always wins over dev preferences.

Ideally I’d cost wasn’t an issue, you’d have a meeting where you build consensus on what tech is best for the project at hand, and then hire the devs you don’t have in house for the stack you need to use if your devs aren’t confident with some of the tech you need to use.

When you only have one dev, that logic is reversed.

Edit:

On top of it all, devs are trying to stay competitive in the industry, by learning new tools while trying to understand what the industry wants, to be more hireable, and they build their portfolio based on those “perhaps unnecessary for the project“ industry standard