It's not really fair to say people who have concerns about the use of home dopplers are imposing their insecurities on others, runner. Of course it's every individual's choice whether to use one or not, but there's nothing wrong with people trying to make others aware of the potential dangers they pose.
There's plenty of advice from professionals - eg the RCM - saying that they caution against the use of home dopplers as they can provide false reassurance and prevent women seeking medical attention when needed, or on the other hand can cause unnecessary anxiety if a woman can't hear her baby's heartbeat when she expects to.
For example, here's a quote from the RCM:
'We advise against personal Dopplers as it takes considerable training to use them properly,' says Jane Munro of the RCM. 'It can cause needless stress to a pregnant woman when she cannot pick up her baby's heartbeat. It can lead to raised blood pressure in the mother and premature births.
'More worrying, we've had cases where there has been something wrong with a baby and the mother has been wrongly reassured after hearing her own heartbeat, or the sound of blood pumping through the placenta, leading to a dangerous delay in her seeking medical attention. In at least one instance, sadly the baby died.'
Source: www.dailymail.co.uk/femail/article-2648933/Pregnant-paranoid-The-mums-buying-DIY-ultrasound-devices-check-babies-frightening-consequences.html
Those of us who have mentioned the problems with home dopplers are just trying to make others aware of the issues and the professional advice about them, not trying to "impose insecurities on others" as you put it.