They would also break somewhat often. Now that I've come to appreciate a plywood-tight batter head, they last for years. I also haven't broken a batter head on my snare in years. What's more, I used Remo CS Black Dots, Ludwig Silver Dots, and other very heavy heads when I was young. Snare head Snare-side heads are very thin so they have maximum response and don't choke the snares.
Tension dictates snare response and also affects the overall pitch of the drum to some extent.
As you might guess, loose snares will produce more rattle or buzz. Tight snares produce a quick, crisp, dry snap. But don't go overboard on tension. Once the snares get to their peak tension, any more tension will cause them to lose response and choke. Type Early snares were made of gut.