Regarding weather sealing, I’ve used a Canon Rebel, extensively, out in the rain with no problems. In fact, if you want to see what a lowly Canon Rebel can withstand, watch this torture test video:
https://www.youtube.com/watch?v=FWzsXeXCwuc
Yes, they poured two cups of hot tea on it, dropped a PC on it, burned it with a torch, mounted it onto a tripod then kicked a soccer ball at it…and it survived just fine. In fact, after all this abuse, then went out and took photos with it…on a rainy day, no less. And that’s with a cheap Rebel body!
As for choosing the 70D over a 7D, not everyone wants to lug around something as big and heavy as a 7D. And obviously, a 7D doesn’t have an articulating LCD, fast Live View AF, built-in WiFi, nor does the 7D use SD cards that you can plug into any laptop. There will be plenty of people who will be choosing a 70D over a 7D. I would.
Started out doing photography at the age of 6 using an uncle's old 1940 kodak brownie box camera. At 15 years of age, I decided to buy my very own 1975 Praktica SLR camera. I now shoot with a Nikon D850. I do unpaid TFP and commercial paid work.