Why is there a hold rating on shares? Or more specifically, why hold shares with a hold rating, as opposed to buying ‘buy’ shares.

I know broadly speaking hold shares means the share is expected to perform roughly in-line with the market. And buy shares are expected to outperform the market. But wouldn’t it make sense to sell hold shares, because there’s more money to be made on strong buy shares. Assuming the reliability of the buy/hold/sell ratings. Or are these not that reliable?
On a connected question, let’s say you had 1000 shares of something that slowly, incrementally increasing in share price. If you sold after it went up by 10% say, and then bought it again shortly thereafter, and it went up a further 10% over the next year, say, would you make the same profit overall if you hadn’t sold it and re-bought it in the middle? I’ve always wondered this.