Not quite. There are some Core branded CPUs that support ECC, including funnily enough the i3's.
Hell, there are Celeron and Pentium chips that they have it enabled on. Not because they expect desktop users to buy them, but because it allows them to keep their Xeon brand premium while letting OEM's like Dell advertise the T140 "starting at $549" (in a configuration nobody would ever want to buy).
For example in the 7000 series, the i3 7100 has a 3.9 GHz base clock and you have to go almost to the top Xeon (the equivalent of an i7) to get anything equivalent. And even then it's a turbo, not a base clock, so in principle the motherboard should not let you turbo forever (PL2 time limit may actually be enforced on a server chipset).
Also depending on workload you may not even be able to exploit an increased threading capability anyway, without 10 GbE on the box, or link aggregation capability.
The Celeron and Pentium chips that have infiltrated entry-level servers are absolute trash though.
It seems like it's mostly any chip that would compete with the Xeon-W gets ECC removed.
That said, the new Xeon-W series has more memory channels (6) and supports more RAM (up to 2 TB) than any existing Threadripper product. I.e., AMD doesn't have an equivalent product for all use cases yet.
However, we don't know the Zen 2 Threadripper lineup and the frequencies for the different Zen 2 Epyc SKUs are also not public yet. AMD could release Threadripper with support for RDIMM/LRDIMM or Epyc chips with higher clock speeds to better compete against Xeon-W.
AMD doesn't disable ECC support entirely on consumer CPUs like Intel does, but as far as I know it's also not officially supported and guaranteed to work, it's up to the mainboard vendor how to handle this. In the Intel case you simply can't get ECC with non-Xeon CPUs.