The problems with observation data is real—

 randomized trial, U.K. researchers identified 519 patients (mean age, 68) with mostly moderate COPD (mean forced expiratory volume in 1 second [FEV1], 50%), ≥2 exacerbations during the previous year, and no cardiovascular (CV) indications for β-blockers. 

Patients were randomized to receive the cardioselective β-blocker bisoprolol (initially 1.25 mg daily, titrated to 5 mg if tolerated) or placebo.

At 1 year, no significant differences were noted between groups in incidence of COPD exacerbations or in other important benefits or harms.

Cardioselective β-blockers remain appropriate for COPD patients who have valid cardiovascular indications for their use, but taken these two studies together suggests that COPD patients without such indications should avoid bblockers—even cardio selective beta blockers

https://jamanetwork.com/journals/jama/article-abstract/2819083