Do you mean digital influencer in the sense of social influencer? The latter can be measured quite well, depending on the method.
Using affiliate-like CPC click-through links on their social media accounts allows the ad network to observe exactly what is working. The problem is that social influencer status probably only really works for stars with a huge following of real life fans. One example (@work) was a celebrity posting about a nice pair of shoes. Those sold out within minutes, and the shoe company's store page crashed due to the unexpected demand. So it can work, but like most things in marketing, if everyone does it, it won't work for most.
Yes, that is what I mean. It can be measured in that way if the product being advertised is something that's meant to be bought right now, online. But many products don't really work like that.
For example, we did multiple campaigns for major sports teams. How are they supposed to measure the impact on sales of tickets and memorabilia? The idea isn't to generate sales of product X right now, it's to energize and grow your team's fan base, which will hopefully lead to more people buying more things over time.
Another example: we did many campaigns for food and beverage brands. People don't tend to order those things right now, online. You're just trying to grow your brand in hopes that more people will buy that snack or drink the next time they're at the store.
So I amend my previous statement to agree with you that semi-precise metrics are possible if you're trying to get someone to buy a specific product online right now. That description covers a lot of companies, and they probably have good metrics.
But a big consumer-goods company like P&G probably isn't doing that kind of marketing. They're trying to get you to think of brand X the next time you're getting groceries. That makes impact of ads devilishly hard to measure, regardless of whether the ads are online or on TV.
I think you're overestimating how well social influencers can be measured. It's true, you can measure clicks to a landing page, one per influencer - but that's relatively annoying administratively, and only measures clicks, not sales. Plus, that counts on your influencer actually following instructions and using the custom landing page URL, which is harder than you might think.
If you're a consumer lifestyle or luxury brand, most of your sales are in-store and hence attribution due to influencers becomes incredibly difficult.
What many companies I've seen do is attempt to measure organic reach through a variety of internal or external scoring mechanisms, and using engagement as a proxy for reach. So a beauty influencer posting a screenshot of her travel bag with your brand tagged would have comments, likes, reshares/regrams measured, and then have that scored as some sort of an effectiveness index.
Its can be pretty straightforward if you run your campaigns through a software platform. The way we (mavrck.co) do it is we do outreach for a campaign, screen the influencers based on their engagement rates/relevancy, have influencers connect their instagram/facebook accounts to our platform, generate individual tracking links for each influencer, ingest their posts via API, and measure the comments/likes/clicks/conversions with our analytics.
Wouldn't that qualify as operating an ad network on instagram, something that is explicitly forbidden via the instagram terms of service?
"Don't transfer any data that you receive from us (including anonymous, aggregate, or derived data) to any ad network, data broker, influencer network, or other advertising or monetization-related service."
Using affiliate-like CPC click-through links on their social media accounts allows the ad network to observe exactly what is working. The problem is that social influencer status probably only really works for stars with a huge following of real life fans. One example (@work) was a celebrity posting about a nice pair of shoes. Those sold out within minutes, and the shoe company's store page crashed due to the unexpected demand. So it can work, but like most things in marketing, if everyone does it, it won't work for most.