But the issues with those two were mainly because of built in batteries right?
I can easily imagine that being the case if they were soft lipo packs. Much more easily than faulty wiring/soldering, bad analog components or a bad chip. That stuff generally works properly or not at all. They can only work in one way. The components get damaged and stop working when something in the chip or the rest of the circuit doesn't work right. And hopefully, if the designers are smart, they build their devices to fail in that way. Sometimes, they don't even have to.
I just don't see a lot of ways for these devices to accidentally do something bad to your batteries... ...chargers would be my only concern when it comes to that. Those easily can.
Lipo packs don't handle shock nearly as well as lithium cells do. Drop them too hard and they can short internally. Denting or getting knocked around at different points in the manufacturing process is also a concern. I mean, being fixed in a metal enclosure probably helps a lot, but even then, a significant enough impact to seriously damage them is still possible... ...maybe even being mishandled in transit can be enough. There's often not enough between the case and the battery to buffer the shock.
I don't think they're so fragile that this would be common at all, but you really don't want to knock them around. You won't necessarily know immediately after damaging it that a cell in the pack is frying itself. I've always found the practice of putting lipo packs into something that is often dropped questionable. It's not like these devices are blowing up left and right, but it does open the door for that to happen.
And then there's the fact that if an integrated battery does vent, then there's no quick way to remove it.
Integrated chargers for integrated batteries are sketchy, too. You have no way of seeing how the battery is doing. You have to blindly trust what may or may not be a reliable charger that's charging to what you can only hope is the proper voltage.
Mods can fail and you can't control that, but that's not the main danger, imo. It's the batteries, which fortunately is something you have control over. Ruling out user-error and bad lipo packs probably eliminates 99% of the already minuscule number of exploding regulated mod cases.
Really just a hunch, but I wouldn't be surprised if it was true. One thing is for sure, though. You'll never know from following the news reports. Someone who makes regulated mods would be a better source. I'd really like to know what the people who implement all of these chips think about these things.