Great points here! I agree with you that there are people who chase after novelty and don't complete most of what they start. If the person is naive about it then I would be weary about hiring them, but it depends on the persons motives.

If they are doing it to experiment with a new library/framework then finishing may not be the point; it could be to see if the tool is worth the hype or if it adds unnecessary complexity.

This exploratory tinkering has been good for me personally because it has developed my sense for parsing out the bullshit used to market new tools.