I don't think it's damaged the brand directly.
But let's imagine the game was a huge hit. Does everyone here think the impact on the tabletop game would be exactly the same as it is now? If the game was a big success, wouldn't at least a little of that translate into new interest in the tabletop game? Isn't that part of the point of WotC's approach? Whether or not the multi-media thing is the best approach.
Or looking at it from another angle...let's imagine they took all the money invested into SCL and directed it elsewhere...do we all really think that nothing better for the game and this hobby overall could have been produced? Just for the sake of discussion, take all the money and manpower that went into SCL and instead invest it in an online tabletop designed specifically for DnD. Or for the money I'm sure they could have come up with a line of short, softcover adventure modules in support of the core books.
And although I'm sure people will shoot those ideas down, those are just a couple off the top of my head. There are likely many more.
So it's more that SCL has failed to help the brand. It's a missed opportunity. Personally, I'm not at all upset about it. I bought it and then requested a refund, an I got it. And honestly, if the whole hobby collapsed tomorrow, I'd still be fine with what I have to play to the end of my days. But I do see SCL as a failure (so far, maybe they can salvage it) and any such failure impacts the business.