Trading Fractional lots of Eur/Usd vs M6E

I have experience trading stocks and ES and this is my first forex into forex. My question is, if you can trade fractional lots of Eur/Usd like .50 0r .20, why would anyone trade M6E?

M6E - what does it mean? Members here are not familiar with stocks terminology so you may not find adequate reply here.

M6E is the micro version of the Eur/Usd

Forex brokers allow to trade micro lots like 1000 units base currency but such trades are likely B-booked, i.e. fx broker makes the market for you. It’s perfectly fine for CFD contracts though which are OTC in nature and require some dealer as a counterparty