In most blackjack games the dealer stands on all 17’s. Doesn’t matter if it’s a hard 17 or a soft 17. However, there are some casinos whose house rules allow one or two or most of their dealer’s to hit a soft 17.
For players this is a good thing and a bad thing.
On the surface, a dealer having to hit a soft 17 looks pretty good. Just the total of 17 sounds high enough to bust. But you have to remember that Ace. The dealer, just like any blackjack player, can reduce that 11 to a 1.
Luckily for blackjack players a dealer will still most likely bust a soft 17. Reducing the Ace to 1 does help them to save their hand, but they are still sitting high enough that they still have a good shot of busting. For example, a soft 17 is made up of an Ace/6. The dealer hits and receives an 8. They have to reduce that Ace, so their new hand total is a hard 15. The dealer has to hit again that is a 7 or higher will bust him. Overall the dealer has more of a shot of busting with a soft 17 than when he has to stand.
You can see how the chances of busting are higher.
However, because the Ace can be reduced, the dealer still has a shot of not busting. When the dealer doesn’t bust he has a greater chance of having a final hand total that is more than 17. Because of this the house edge goes up in favor of the house to the tune of 0.2%. And that’s a pretty good chunk.
Because the house edge of a game that allows the dealer to hit on a soft 17 is 0.2% higher than a normal blackjack game, players tend to avoid these games.