For big public companies, it's the opposite. If a company wants to fundraise 10% of its market-cap, either for an acquisition or major investment, it doesn't require nearly as much effort. It can issue new shares, and immediately sell them to investors the next day for cash. The hard part is finding profitable investments, not raising the funds to make it happen. Hence why there's little competitive advantage in hoarding cash.
On the flip side, having a big cash hoard is bad for your investors' returns. It bloats your market-cap, without having any impact on earnings. This means that your P/E ratio is now inflated, and your earnings yield is reduced. From an investor's perspective, if you have invested $100 in the company, you're only only getting back $6 in profits every year, not $7 or $8.
Another way to look at this, is that Google/Apple invest their cash hoard very conservatively, in things like short-term treasuries, because of which their returns are very low. Whereas most of their investors would far prefer to invest the money in investments that produce better returns, such as the S&P 500. By not returning the cash hoard to its investors, Google is essentially forcing them to make low-return investments that they would never make otherwise. Of course, investors aren't going to be happy with this, and they will retaliate by lowering their valuation of GOOG stock, thus depressing the share price.