Only very old webs are ... dirty.
I'm pretty good at identifying the dangerous spiders now (i.e. distinguishing brown recluse from wolf), but it took several instances of trapping the spider under a glass and then breaking out my cell phone and looking at lots of pictures.
If your area has lots of kinds of dangerous spiders then it might be more of a pain, though.
I think what the parent comment was worried about was painful bites more-so than death (though that's also worrying).
I generally avoid killing/ removing spiders (they also prey on moths, keeping clothes etc hole-free), wasps too to an extent (but they are still largely a pest).
The Bedbugs were quite easily eradicated with insecticide around and under the bed, but that's last a resort as it is toxic to virtually everything (including pets and humans), something I don't doubt as the smell is more irritating than Ammonia. I'd much rather use natural remedies (especially when you don't have to do anything), than strong chemicals that we don't truly understand the effects on the environment or the food chain.
Diatomaceous Earth is a dusty substance made from the shells of tiny sea creatures. The shells are so tiny (and then ground finer) they wedge into the exoskeletons of insects and eventually kill the bbugs. But it's pretty safe for larger animals and safe for home use
I haven't had to deal with bed bugs specifically, but I've read that using a steamer or clothing iron (best with steam) will effectively kill them. You can steam most carpets, floors, beds, etc.
I live in a very humid area and bugs are a huge issue during the summer. I've sprayed the inner frame of one problematic window with insecticide (deltamethrin - lasts months), steam just about everything in my home every week or two, and regularly run all blankets and upholstery through my dryer's "sanitize" cycle (steam + 165F air). There's an occasional spider, but rarely see anything else... no mites, nothing.
Of course there are plenty of things I don't see, but I do my best to keep it all at bay.
So, there are birds, bats, fish, spiders, lizards, geckos, other bugs, ...
Later it came out that Purple Martins much preferred dragonflies, which are a more effective mosquito eater.
If we lived in forests mosquitoes won't be a problem, well at least all those activities increased GDP.
No, not really. That these eat mosquitoes makes it clear that they don't wipe out mosquitoes, or they'd have died out for lack of food.
They may keep populations down to some extent, but any predator that wipes out its prey winds up dead quickly.
If you truly believe nature itself is perfect and human inventions are stupid, leave the comfort of your home / office and try to survive buttnaked in the jungle, all by yourself.