There's a difference between tennis shoes/running shoes and trail running shoes.

Trail shoes will offer more protection and have a stiffer sole. That gets you (over the long term) a lot better support. Running shoes made for paved surfaces won't have the tread or the stiffness needed to keep your feet happy over the long haul.

A lot of ultralighters do use street shoes for hiking, with mixed results...

All the benefits of the shoes you wear, plus the benefits of having a shoe made for hiking, can be had with a trail runner. I've been using trail runners for a number of years, with no problems once I find one that fits. Street shoes - yeah, I hiked in some "walking shoes" on a trail. When I hit a slippery patch I fell flat - I wasn't expecting it, since in my trail shoes I wouldn't have had a problem. But down I went... Just not the same.
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