But what's the alternative? Unsafe home network where one rogue device can act as a tunnel for bad actors(bots more often tbh)?
If you're worried about your network being saturated for DDoS by a random IoT device, I suspect you'll notice it even without explicit monitoring.
Besides, risks need to be weighed by their probabilities. It's a small chance of name-brand IoT devices "going rogue" vs the certainty of random things not working when they should, and I don't think this tradeoff leans towards VLANs for most people.
Prevailance of home ip addresses in DDoS attacks and in proxy pools does suggest so ¯\_(ツ)_/¯
Vetting devices you introduce to network is of course solid advice, but a little bit of paranoia never hurts in tech.
My whole point above that it does actively hurt, with devices randomly misbehaving at exactly wrong times. It's not enough to set up everything once because devices get updated and change ports, domains, and protocols. It also makes everything more brittle, requiring multiple inter-VLAN proxies to be running at all times for seemingly unrelated devices to work. That SD card in your raspi died? You decided to update Docker on it and run into problems? No Sonos for anyone in the house until it's fixed.
There's a real cost to that paranoia, it's just another case of security/convenience tradeoff.