It is an excellent source of organic matter to build soil tilth, and also of many plant nutrients. If you choose to use manure, follow sensible rules and exercise caution. I've Had Trouble with My Tomato Plants for Several Years - Late Blight Problems. I've Tried Moving Them, but it Hasn't Helped. Blight diseases are always most troublesome in cool, wet summers.
Sanitation is very important.
Immediately get rid of all the dead vines and fruit. The fungus can live in decayed plant refuse in the soil. Do not compost infected plants. Planning is the next step. You were right to move or rotate the crop.