I'd like to point out a few things:
Charging batteries overnight is not an issue if you are using a smart charger. Unless you are using a "dumb" charger that keeps charging the batteries even when its full. The only issue you may have with charging overnight is that you may increase your energy consumption by some watts. Smart charger automatically cuts off charge once the phone/device is full.
Charging a battery with a low current will not damage the battery if the battery gets to be fully charged. The danger, to a battery, lies in charging with a high current or voltage. It is even recommended to use a low current charger as you can charge your batteries so that it won't heat it up. Slow charging is the best for most batteries, only some batteries can take fast charging at high current without deterioration. That is possible with the use of Quick Charge charging system with up to 5A charging current-only very specific phone hardware and chipset support these high current charging features.
In your first point, you've used a clause "if". The word "if you are using a smart charger" is not meant for all. So to some, it would be a problem and to others using a smart charger it won't but IN A LONG RUN it would be according to Battery University and Science Alert
I already said this in the article. The word in a long run means months, years. Very slowly in action that no one will never get noticed until many months or years.
As your second point, you are right and I'm not also supporting of charging battery with high current, but only with a normal voltage (moderate).
On using low current to charge won't affect the battery truly but u gatto be ready to spend more hours charging ur phone especially if it's a battery capacity like 5000 - 6000mAh.
And mind you, low current differs. Not every low current can power a charger. Every charger are expected to have at least input of 100 - 240v(50/60Hz, 0.3A, 0.6A, 0.9A etc depending on manufacturers ratings). If you have a current below 100v you know what that means.
Thanks for your contribution @greenrun
I've read the battery university link you dropped, I still did not see anywhere where it said charging with a smart charger is detrimental to a battery health. I'd ran a real-life tests with variety of batteries for more than eight years, in my experience I've never seen where a smart charger destroyed a battery simply because it was plugged in.
What do you mean by above?
The low current I'm talking about is not one given out by charger as a result of voltage drop. I'm talking about chargers outputting specified charging voltage and current as made by a manufacturer. Also the DC voltage output is the required nominal voltage value required by the said battery.