SIs are just people that have made at least 250k for the last 2...

SIs are just people that have made at least 250k for the last 2 consecutive years or net assets of at least 2.5mil. That just needs to be certified by your accountant.
It is usually cheaper faster, cheaper and easier to do placements to SIs than rights issues.
Even when a SI has a long term interest in a company, they often end up with a much larger position than they bargained for and thus distributes the shares, which also means more cheap shares for anyone who wants them.