Seriously though that's awful, sorry to hear that and glad you came out the other side (relatively) unharmed.
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.
Drugs are illegal for a good reason. What did you expect?
Your friend lost his mind, you narrowly escaped death and you blame the government for making this substance illegal? Correct?
These drugs were legal at the time. I blame myself for my own actions(but it was almost a decade ago and I have moved on, which is why I'm comfortable being open about it), but blame is not always singular. The state is also partially to blame because they banned all the good drugs, leading to grey markets with dangerous, untested, experimental drugs.
As for my friend, I had nothing to do with what happened to him, I only met him after the fact.
Why did I do this? I was forced to do drug tests for cannabis more or less against my will(under duress). And I was a stupid kid who wanted to get high, and these horrible drugs were easily available, advertised as not showing up on tests, etc.
I have the chief responsibility for my own actions of course, but it's hard to ignore the fact that none of it would've happened if not for an extremely draconian and outmoded approach to drugs.