Are long lines dangerous for dogs?

I have a long line which I've used with my (now 7 month old) puppy, which I clip onto the back of her harness.

This weekend we took her to an off leash dog beach. The beach is very big and wide, so I was planning to avoid other dogs as much as possible and let her play in the water.

However, there was an incident where an off leash dog ran to my dog and away again and my puppy spun around and ran after it, straight into the long line, getting the line wrapped after her leg and neck. I released tension on the line to not hurt her and was able to call her back to untangle her, but with the other dog running through the line as well, she could have been hurt so easily.

So I'm thinking of hanging up the long line for good. I have always been careful not to leave excess line out (I keep it wrapped in one hand and feed with the other hand), but it quickly turned dangerous regardless. I always thought long lines were great. Have I been ignorant or just unlucky this time?