You're mixing up revenue share and profit share - JSA's revenue share comes to retainers regardless of whether the firm makes a profit. Algo seems to rely on turning a profit prior to payout.
I find this a bit odd. JSA has had a "profit-sharing" model since forever. Of the billing that even associates do on each matter, they get a percentage of their billing. This is directly linked to the profit earned by the firm. Plus, at the end of the year, the firm gives some additional bonus as well. So how is this Algo model any different?
plot twist, they're not making a profit and senior associates are now taking a salary cut to invest in the business in the hope of profit-sharing one day. Algo is building its own angel investment scene and the fee earners below the senior associate level are working to fund raise for Algo.
In any case, if they do become big someday, it would be an interesting place to work at.