This is simple: no one remotely like them has come remotely close to winning a presidential nomination in the modern era.
They may have political talent. Republicans can like them, even a lot. But they're either deluding themselves (and they wouldn't be the first politicians to be so afflicted) or their real plan is to use the attention to further some other goal. Neither of them, at least so far, offers anything new in the way of policy, so their candidacies aren't about changing the party in that way.
"Vote for me, I'm just like the others but less qualified" might be a strong pitch to some Tea Party voters. But it isn't going to get Fiorina or Carson anywhere close to a nomination.
Will their candidacies matter at all? Scholars of presidential nominations are somewhat split on this question.
Almost any candidate can receive a fair number of votes in Iowa - 10 per cent, 20 per cent, perhaps more - because anyone can benefit from a well-timed burst of publicity. And we know where the votes might come from. Carson, for example, is fishing in the same waters as Mike Huckabee, Rick Santorum and perhaps Ted Cruz. So, if Carson does well in the caucuses, he'll hurt those candidates.
Does that matter?
Making the strongest case for the proposition that party actors control the nomination process, the answer is: no, not really. What matters is how the party's politicians, campaign and governing professionals, donors and activists, formal officials and staff, and aligned interest groups and media think about the candidates. If they support Huckabee and he does poorly in Iowa because Carson surged, they'll stick with him. When Carson fades, Huckabee will still be there.
This is pretty much how I view the process. Primaries and caucuses aren't irrelevant. Party actors take stock of the results; they may also consult polls in gathering evidence on which candidates are likely to do well in the general election. But those (relatively) sophisticated observers won't (usually) be thrown off by the complicated dynamics of a multicandidate field.
On the other side of the spectrum are scholars who believe things haven't changed much since the 1970s, when the primaries and caucuses were kingmakers. If these experts are correct, then the effects of the enhanced media exposure and the momentum candidates acquire are extremely important.
In other words, what happens in one primary directly affects the next one, and so on. Party actors can be important because they provide resources to candidates, but that help might not be enough to overcome the effects, even when random, of primaries and caucuses.
If this view is correct, then Carson and Fiorina can potentially have a big impact without coming close to winning the nomination. So, for example, if Jon Huntsman, the former governor of Utah, had surged in New Hampshire and taken some votes that wound up with Mitt Romney, then Romney might have been in danger of losing the Republican nomination.
But if the "party decides" argument is more accurate, then Romney was going to win either way. Tim Pawlenty's failure to take off and then Rick Perry's implosion in the debates probably wrapped it up. All that New Hampshire changed was how quickly Romney was able to end the visible parts of securing the nomination. Santorum's narrow win in Iowa and Newt Gingrich's upset in South Carolina delayed the eventual outcome, but it didn't change it.
There's evidence for both scenarios, making it difficult for scholars to resolve. Just bear that in mind when pundits start talking about how Carson, Fiorina and other wild-card candidates might change what happens in 2016.
The author is a Bloomberg View columnist