||You pick a thing, here and there without reading the whole thing. The Mesilat Yesharim only allows Chumra (extra restrictions) after you are doing everything 100% perfect. Read the whole book, not just bits and pieces.
The Gemara shows a difference in the generations, yet in the later generations the Gemara Rabbis did it the easy way out, did they not?
There are times when we should follow both opinions and there are times that it is not allowed. Carrying on Shabbat even in a city with an Eiruv around it is certainly a time to be Machmir (strict), because 10 or so Rishonim (early Rabbis) say it is not permitted and you would be sinning to an extent that you would deserve capital punishment. That we ignore, but we're real careful about waiting 6 hours after dairy Bliot (absorbed flavor) that doesn't really exist. That we keep?!