@shiner3237 , If the dust cover is attached directly to the platform the plater and tonearm are attached too then it can be a problem open or closed. However on suspended turntables where the platter and tonearm arm are attached to a sub chassis that is suspended within the plinth and the dust cover is hinged to the plinth isolated from the plater and tonearm, dustcovers are a huge advantage. They protect the record and tonearm from dust and attenuate the sound getting to the cartridge by 10 dB and since they are isolated from the plater they can not pass on any resonance. They are hearing protection for your cartridge! Turntables that are designed like this include some Thorens designs the Linn LP 12 and the Sota turntables. People who do not use a dustcover during play are grinding incidental dust into their records. You you have a turntable that is not suspended and isolated and can not use a dust cover during play the solution is to get an isolation platform and have a dust cover made to fit around it.
IMHO if you can not use a dust cover it is because your turntable is poorly designed. (that should raise some eyebrows:-)