Why bandwidth consuming ddos attack using only udp or icmp?

Hello, list.

I have operated network in my company and recently I have experienced
some ddos attack(inbound) on my network.

It seems that the ddos attack was divided in two

first, the bandwidth consuming attack was all consist of udp or icmp using big 
size packet(about 1500 byte).
second tcp based attack for example http(80/tcp) is mostly creates lots of pps 
using small size packet(about 40 byte )

So, some network administrator said that he filtered all udp and icmp
just against the bandwidth consuming ddos attack at the border router.
(Surely some problems would be happen..dns..somethinf like that)

and I have one question.

Is it impossible or ineffective using tcp for bandwidth consuming attack in the 
point of attacker?
anyone who saw the bandwidth consuming attack using tcp?


Thanks in advance.

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