To be honest it is smart to filter some outbound ICMP both router level and software firewall level as a extra layer of security.
It my not be pertinent to stopping a DoS or DDoS but malicious people still use ICMP to try and retrieve as much information about a network as possible before they attempt to breach it.
I am not saying they ONLY use ICMP but that is one of the few packet types they use and depending on if you have you're flood gates open they can gain a great detail of information in very little time.
Take some time to google and look up information about how NMAP and a few other programs utilize ICMP as one of the resources to gathering information then base your filters off of what you feel is necessary to protect yourself and your network.
If at all possible set up a internal test network (I personally bought a secondary wifi router a cheap one and have a secondary pc as a firewall to test all of my router/ipchains/software firewalls settings before I employ them across my main network for my household and any customer that hires me to secure their networks.
I highly encourage people to try and do some research on port scanning and how to breach firewalls on their own network so that they can better protect themselves and any family they are helping.
Here is a couple of resources I have used and referred friends to prior.
Sans Information Security How ICMP is used for Reconnaissance
InfoSec Institute ICMP Attacks
Some of the attacks are no longer viable but there are newer forms of Smurf that work still because of how the programmer was able to re code the original attack and change how it works and uses resources.
Dig around and google is your friend along with Stack Exchange and also duckduckgo search engine is wonderful for resources that google might filter out just be cautious and use your wits!
I have been a pc tech for 22 years and a network security specialist for 10
I am currently in chool for my ECH and my CPTS and I am looking at Offensive Security courses when I finish these.
Hope this helps and others find this information useful as I restore backups I made to this system and I find my other links and resources on this matter I will update this answer.