Until recently the US preventative services task force had been recommendeding low dose aspirin to petty much everyone over a certain age for prevention of heart disease and ischemic stroke. They recently ended this catch-all recommendation for everyone above a certain age, but there are many situations in which a low dose aspirin is still going to be helpful for certain people. Low dose aspirin has a low risk of major side effects, but if what it's preventing is also rare then it might not be worth it for everyone. So it's no longer a catch all recommendation above a certain age, the decision needs to be made in conjunction with a patient's doctor based on their particular health situation and risk benefit balance. Age is another thing that may affect this balance, for instance this study was specifically looking at older adults where bleeding events are more common than in younger or middle aged adults, and shouldn't be generalized to all adults.

For secondary prevention (like someone already has evidence of heart disease or a past ischemic stroke), there's volumes of evidence showing it's benefit. Sometimes even two different antiplatelet drugs, like aspirin and clopidogrel, are even used together.