It's not available because no smart investor has found a way to make it work ... yet. I'm not sure we can extrapolate Jeff Bezo's particular motives for investing in Basecamp into a widespread market solution. Back in 2006 when DHH said Bezos made the investment, Bezos was already worth ~4 billion.[0] In other words, being a multi-billionaire allows the luxury of making some investments "for fun" instead of worrying about being fired as a manager of a fund.
In my 2 previous posts[1][2], I attempt to explain the logic of why VCs / hedge funds / private equity ... do what they do and why they care about "growth".
So, one way to make it work is that you (the royal "you" as in the daring contrarian maverick investor) prove to the world that you can take some money and make it earn 8%+ returns by doing what DHH suggests. Nobody prominent has done that so nobody copies them and therefore, the "market solution" looks non-existent.
Does everyone want a new alternative asset class that simply buys minority non-controlling stakes in smaller companies and just takes a slice of the dividends? Let's call it the SmallCoDividendsFund. Ok, show the world how you reliably return 8%+ every year from DHH's strategy and limited partners will be beating down your down door to give you more money! You don't have to write essays evangelizing the alternative investment thesis; instead, just invest real money in SmallCoDividendsFund, get awesome returns, and all the media outlets will provide publicity and encourage copycat investors.
[0] https://en.wikipedia.org/wiki/Jeff_Bezos#Wealth