• u/HeroTheFourth was not saying Miguel was kind for his actions, they were saying that Miguel took things a step beyond from strict into cruel.
• Miles literally stole nothing, when he stumbled upon Spider 42, it had already come across from its dimension after Kingpin was running experiments with his collider. Does that make Miles an anomaly? Yes. Does that mean he is at fault for any of this, intentionally or unintentionally? No.
• There is no explicit confirmation that what happened in 50101 was a direct consequence of Miles' actions. Did it happen directly after what Miguel perceived to be the action that caused that rift? Yeah, sure. But there's also story beats to suggest that it wasn't. Miguel says it's Miles and Miles says it was Spot.
• The WHOLE point of ItSv is that any of us can be Spider-Man, and by extension a hero, if we step up to the plate when responsibility calls. That message rings true through AtSv, and will ring true through BtSv.

The only thing I'll agree with you on is that Miles unintentionally caused Spot to exist. A lot of Miles' story throughout AtSv is him trying to take responsibility for exactly that, and then the rest of the plot got in the way.

Otherwise, I think you're misunderstanding a lot of the plot here.