The primary drawback I see to using Steem Power in this way is that Steem Power is currently used for a number of key blockchain calculations.
- Determine the strength of your voting power.
- Determine an account's bandwidth limit.
If Steem Power could only be acquired through social means then there is a steep barrier to entry to use Steem. It very quickly degrades into the "haves" and the "have-nots". The "haves" control the distribution of the printing press and then, by consequence, the bandwidth on the blockchain itself. There would need to be some fundamental changes on the blockchain much deeper than the acquisition of the currency to counter these effects.
I would argue that the ability to buy Steem and power it up to gain influence is key for it to be used as social capital. Regardless of whether we like it or not, money is a proxy for social capital. We use it to shortcut the process of reviewing each other's qualifications. If I wanted to jump start my social capital I could spend thousands upon thousands of dollar on a nice suit and buy a plate at a high class charity banquet. There is an assumption by those in attendance that every one else in attendance is important because they paid the entry fee.
Steem Power has the same effect. We assume those with a lot of Steem Power are important. Either because they earned it and deserve my respect or they are a huge investor in the platform and they deserve my respect because they believe in Steem and want it to be successful. We run into an interesting problem now because the power down period is two years. There are users trying their best to get out of Steem yet they still hold a lot of weight with the community. This is counterintuitive to what Steem Power is supposed to stand for and creates demand for a currency that accurately represents what Steem Power is supposed to represent.
I think a better analogy for this is paid promotion (not exactly the current minimal model of it). It gives you visibility and access, which can and very likely will lead to actual social recognition (high SP votes).