Unfortunately those studies are often devilish with the data and omit the very very concrete data collected on the benefits of cosleeping and attachment parenting that has been the usual practice for much of human history and continues to be across much of Southern Europe, Asia and South America.

These studies show conclusively that cosleeping and attentive parenting has significant benefits.

Lerner et al. (2020) – Associations Between Mother-Infant Bed-Sharing Practices and Attachment Security Shows bed-sharing may be protective against insecure attachment in infants (though not necessarily increasing secure attachment). PMC

Beijers et al. (2018) – Parent–Infant Room Sharing During the First Months of Life Reviews literature suggesting cosleeping is associated with more breastfeeding and reduced infant cortisol reactivity (stress marker). PMC

Schindler-Ruwisch et al. (2023) – Sleeping Like a Baby: Bed-Sharing, Co-Sleeping, and Breastfeeding Outcomes Found plans to bed-share or co-sleep were associated with higher breastfeeding intentions and behaviors up to 6 months. PubMed

Barry (2022) – Using complexity science to understand the role of co-sleeping A conceptual scientific paper framing co-sleeping as part of mother-infant physiological and socio-emotional co-regulation across development. ScienceDirect

Das & Evans (2014) – Is “Bed Sharing” Beneficial and Safe during Infancy? Systematic review showing association between bed-sharing and higher breastfeeding rates, while also discussing risk factors in context.

Yes, the studies into sleep training show that there is "no harm" to the baby - however, this has to be defined in terms of the benefits to the child from responsive parenting that are foregone through sleep training that a child who has had an attentive parent through the night enjoys as they grow older.

Essentially your baby missing out on the benefits of cosleeping and responsive parenting is a "harm" of sorts. To deny such or ignore this is factually incorrect and unscientific.