Why is it permissible to use a stroller and not roller skate on Shabbat and/or chagim?

ב"ה Shalom The question of a bicycle on Shabbat or Chag has been in Halachic discussions for nearly a century. Some poskim said that it is forbidden since a person may tend to fix it on Shabbat or a person may go out of Tchum Shabbat. Neither of the above reasons applies to a stroller. A stroller doesn't have inflated tires which can get a flat; neither does it have a chain or pedals which are stepped on forcefully. Also, on a stroller a person doesn't go at speeds to reach distances out of town and out of Tchum Shabbat. (שו"ת ישכיל עבדי (חלק ג סי' יב וסי' יט וח"ה סי' מ); שו"ת ציץ אליעזר [ח"א סי' כא וח"ז סימן ל) However, some poskim are of the opinion that we can't make new decrees in our time which Chazal didn't say and therefore do not rule out a bicycle for that reason but rather because of "ovdin d'chol"- which basically means that it is because it something that is weekday like, travelling from place to place, shaking and bumping perspiring and so on. This issue clearly doesn’t apply in the case of a stroller, which is something which leisurely pushed at a slow pace. (שו"ת יחוה דעת חלק ב` סימן נ"ב, חזון עובדיה שבת ח"ד עמוד מג Chag Same'ach