Spice is incredibly harmful and it’s just a stronger version of cannabis. It’s therefore reasonable to consider that cannabis may be harmful in the same way, just less obviously so.
But that's about where the overlap ends. There are many reasons for this. The main one is that synthetic cannabinoids tend to be full agonists at both the CB1 and CB2 receptors, whereas THC is a partial agonist. This means that there are effects that synthetics can do that THC simply can't. In addition, they're much, much more potent; some such compounds have active doses in the 100mcg range. Cannabis also contains other compounds that counteract some downstream effects of THC most notably CBD, but also CBG.
Weed is not going to box your kidneys. CB2 is heavily expressed in kidney tissues, and extremely potent full agonist activity at CB2 is probably why they're so nephrotoxic. THC simply just isn't potent enough in doses that can be reasonably consumed.
Synth noids are also extremely vasoconstrictive and this is how they can cause strokes. They have vasoconstriction comparable to meth, moreishness comparable to crack, and immobilising effcts comparable to heroin. So what ends up happening is you binge. Hard. Maybe for weeks, all while remaining mostly immobile between doses. All while pumping your system full of vasoconstrictors. Weed on the other hand can be vasoconstrictive or vasodilating, depending on the relative content of the various plant cannabinoids. And it's nowhere near as vasoconstrictive as synth noids.
It is probably the case that extremely heavy cannabis use can cause enough immobility over time to increase risk of stroke. But it would take years and years, not days.
Cannabis concentrates, e.g. dabs, rosin, BHO are stronger versions of cannabis.