It is thought that the reason Google created the Sandbox new site filter was to stop spam related sites from adding numerous purchased links--and ranking highly for their keywords from the date of launch. Since Google apparently considers a high number of links pointing to a site from the beginning to be rather suspicious, the links are not considered to be natural. Another possibility is spam sites would use various tactics to rise to the top of the search results, and gain heavy sales prior to being banned for being in violation of Google’s Terms of Service; and then repeating the process continually. As a result, new sites are put into a form of probation, usually referred to as the Google Sandbox.
Yes google uses the sandbox as a kind of sin bin of you know what I mean. If they detect extreme unusual behaviour then they place your site at the bottom of the rankings or even completely de-index you. However even if you manage to get out of the sandbox google place negative capacity on your future links so you need even more quaility links than your competitors to even get close to them, so really spamming is definitely not the answer. Stick to high quality links and you will be fine.
If spammers could set up a site, rank highly and start earning money right away then they could do this all day and would not care if their sites got penalized and removed because they could replace it with a new one right away. The churn and burn industry as it used to be called. Spammers created new sites faster then the search engines could remove them. But since sites do not rank right away (at least for competitive terms) it discourages spammers from creating churn and burn sites since they typically have to wait 3 plus months before they can start making money.
yes the main reason of creating the Google sandbox is to protect the search result from spams. and also its hard to remove your site from sand box. if you delay to take decision then you will be buried in sand
To deter and punish sites for purchasing links vs. natural linking. Google wants to offer the end user a better search experience and only pull sites which are truly and organically a real match
That's a bit harsh. I think the Google Sandbox was created to hold new websites in while Google is still trying to see their relevance for the keywords they're trying to rank for. It's like a "waiting room" for new websites while they are waiting for their actually PRs. SERoundtable defined the Google Sandbox and has other interesting articles about it. Hope that helps. Have a good day!