Actually there were quite a few other Color space other than the Adobe RGB & sRGB, but the key issue of why sRGB and Adobe is that|
- sRGB is fully compliant with ISO output device and are fully supported in all kind of media and output ( monitor and print, online, or graphic system )
- Adobe RGB represet the limit placed on Art / Graphic reproduction system and can be used becasue it was first intended for Proofing / Graphic art but now are supported in electronic display media as well as Art Print output. However, Adobe RGB cannot be used direct to most print output. most Minilab like fuji FDI, Noritsu QSS or Agfa D-Lab can support only sRGB. So using Adobe RGB do allow you to capture more, but in post processing for print the question is how to compress the gamut to sRGB or print within that.
Shooting RAW is the answer to most problem, of course that means a good post exposure RAW development workflow is needed !!