It depends on the disease.
If it's a soilborne wilt, the plant will eventually die. As the disease progresses in the plant, fruit will be stunted. Unlike most foliage diseases, soilborne wilts usually cause plants to be fussy and slow in their growth until they suddenly collapse. Most soilborne wilts spread very slowly in soil, so there's no urgency to pull the plant to save other plants just on suspicion. But if you confirm that there is a wilt, it's best to pull plants simply because there's little point in continuing to care for a plant that isn't going to produce well, and you'll need to think about how to deal with the area for the next growing season.
EB doesn't usually require pulling the plant until it's advanced. It's a relatively slow-progressing infection, especially if you prune and spray. Pruning doesn't stop the disease entirely most of the time, but it reduces the amount of inoculum in the plant's vicinity and slows spread. Most sprays available to home gardeners are also not curative--they delay progress by offering some protection to unaffected foliage.
Some fungal disease, like late blight, viruses, etc. will pose a big danger to other plants, making pulling the plant urgent. But you don't seem to have one of those going on.
I agree with pruning any spotty foliage immediately, but I would first take photos of the affected foliage and a snapshot of the whole plant. That way, if things get worse, you have documented the progress of the disease in case you need to get advice/help later.
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