To win independence you need as broad a church (forgive the pun) as possible.
That is what the SNP should be. Fiscal Conservatives, Socialists, Greens, Centrists...whatever. As long as they firmly believe Scotland would be better off as an independent country.
A face to put up against every unionist party that claims to be any of the above and show voters why independence will be better for them.
Just indulging green left wing policies that have been a disaster narrows your voter base and leads to....this.