There's a dilution effect. More is less. As referees, we are constantly being pressured to turn more manuscripts around faster. Quality must be suffering. New journals are appearing regularly.
Old ones die slowly.
Libraries can't afford them. Editors are so overloaded that editorial input into the science is now very rare. Authors feel they have to publish something three times to get heard. Exaggeration of novelty and significance is common. Readers seem overwhelmed.