You can use those VMs. The system requirements are guidelines which need to be adapted to your application and how it behaves with your application under full load. You need to be sure that any resources that you chose will be adapted to your workload.
I use B-series VMs for a large number of ThingWorx workloads and they work great for demos and tests, just be aware that they are burstable so you build up burst credits when the machine is not under heavy use and they are consumed when it gets put under load. If your environment is under constant load, then B-series are not appropriate and D-series would be better. Also watch out for the IOPS. B-series have much lower disk IOPS than the D-series or F-series which might be important for disk intensive activities. That said I run a tiny InfluxDB on a B1ms and it works great.
There is also a 4th generation D-series which will likely be more efficient and cost effective that the 3rd generation.