Well, in practice it never actually does levy more taxes for its spending, and the crowding out of the capital market is kinda the point, since firms cut their capital investments during a recession anyway.
In the long run, it'll be detrimental to the economy, because firms would otherwise shift their capital investments and the government's deficits and artificial support prevent that adjustment from happening. But in the short run - which I think is what this comment thread is talking about, since it's predicting another dip once the stimulus is withdrawn - it really does make for an improvement.
But OTOH, you need only look at the spiralling U.S. govt deficit to see that just because they spend more doesn't mean that they'll raise taxes to cover it. Source on that:
Since about 1960, the top tax bracket has almost uniformly gone downwards, as has the bottom tax bracket, except for a slight blip around 1989. We know what that did to Bush Sr's reelection campaign.
The USA is very special, because they happen to own the printing presses for the reserve currency of the world. Most other governments can't go that route for that long.
